Disable Gravatar.com

For future reference

class simple_local_avatars {
	function simple_local_avatars() {
		add_filter('get_avatar', array($this, 'get_avatar'), 10, 5);
		add_action('admin_init', array($this, 'admin_init'));
		add_action('show_user_profile', array($this, 'edit_user_profile'));
		add_action('edit_user_profile', array($this, 'edit_user_profile'));
		add_action('personal_options_update', array($this, 'edit_user_profile_update'));
		add_action('edit_user_profile_update', array($this, 'edit_user_profile_update'));
		add_filter('avatar_defaults', array($this, 'avatar_defaults'));
	}

	function get_avatar($avatar = '', $id_or_email, $size = '80', $default = '', $alt = false) {
		if (is_numeric($id_or_email))
			$user_id = (int) $id_or_email;
		elseif (is_string($id_or_email)) {
			if ($user = get_user_by_email($id_or_email))
				$user_id = $user->ID;
		} elseif (is_object($id_or_email) && !empty($id_or_email->user_id))
			$user_id = (int) $id_or_email->user_id;
		if (!empty($user_id))
			$local_avatars = get_user_meta($user_id, 'simple_local_avatar', true);
		if (!isset($local_avatars) || empty($local_avatars) || !isset($local_avatars['full'])) {
			if (!empty($avatar))
				return "<img src='" . get_bloginfo('stylesheet_directory') . '/images/avatar.png' . "' class='avatar avatar-{$size} photo' height='{$size}' width='{$size}' />";
			remove_filter('get_avatar', 'get_simple_local_avatar');
			$avatar = get_avatar($id_or_email, $size, $default);
			add_filter('get_avatar', 'get_simple_local_avatar', 10, 5);
			return $avatar;
		}
		if (!is_numeric($size))
			$size = '80';
		if (empty($alt))
			$alt = get_the_author_meta('display_name', $user_id);
		if (empty($local_avatars[$size])) {
			$upload_path = wp_upload_dir();
			$avatar_full_path = str_replace($upload_path['baseurl'], $upload_path['basedir'], $local_avatars['full']);
			$image_sized = image_resize($avatar_full_path, $size, $size, true);
			if (is_wp_error($image_sized))
				$local_avatars[$size] = $local_avatars['full'];
			else
				$local_avatars[$size] = str_replace($upload_path['basedir'], $upload_path['baseurl'], $image_sized);
			update_user_meta($user_id, 'simple_local_avatar', $local_avatars);
		} elseif (substr($local_avatars[$size], 0, 4) != 'http')
			$local_avatars[$size] = site_url($local_avatars[$size]);
		$author_class = is_author($user_id) ? ' current-author' : '';
		$avatar = "<img alt='" . esc_attr($alt) . "' src='" . $local_avatars[$size] . "' class='avatar avatar-{$size}{$author_class} photo' height='{$size}' width='{$size}' />";
		return $avatar;
	}

	function admin_init() {
		load_plugin_textdomain('simple-local-avatars', false, dirname(plugin_basename(__FILE__)) . '/languages/');
		register_setting('discussion', 'simple_local_avatars_caps', array($this, 'sanitize_options'));
		add_settings_field('simple-local-avatars-caps', __('Local Avatar Permissions', 'simple-local-avatars'), array($this, 'avatar_settings_field'), 'discussion', 'avatars');
	}

	function sanitize_options($input) {
		$new_input['simple_local_avatars_caps'] = empty($input['simple_local_avatars_caps']) ? 0 : 1;
		return $new_input;
	}

	function avatar_settings_field($args) {
		$options = get_option('simple_local_avatars_caps');
		echo '<label for="simple_local_avatars_caps">
			<input type="checkbox" name="simple_local_avatars_caps" id="simple_local_avatars_caps" value="1" ' . @checked($options['simple_local_avatars_caps'], 1, false) . ' />
			' . __('Only allow users with file upload capabilities to upload local avatars (Authors and above)', 'simple-local-avatars') . '
		</label>';
	}

	function edit_user_profile($profileuser) {
		?>
		<h3><?php _e('Avatar', 'simple-local-avatars'); ?></h3>
		<table class="form-table">
			<tr>
				<th><label for="simple-local-avatar"><?php _e('Upload Avatar', 'simple-local-avatars'); ?></label></th>
				<td style="width: 50px;" valign="top">
					<?php echo get_avatar($profileuser->ID); ?>
				</td>
				<td>
					<?php
					$options = get_option('simple_local_avatars_caps');
					if (empty($options['simple_local_avatars_caps']) || current_user_can('upload_files')) {
						do_action('simple_local_avatar_notices');
						wp_nonce_field('simple_local_avatar_nonce', '_simple_local_avatar_nonce', false);
					?>
					<input type="file" name="simple-local-avatar" id="simple-local-avatar" /><br />
					<?php
					if (empty($profileuser->simple_local_avatar))
						echo '<span class="description">' . __('No local avatar is set. Use the upload field to add a local avatar.', 'simple-local-avatars') . '</span>';
					else
						echo '<input type="checkbox" name="simple-local-avatar-erase" value="1" /> ' . __('Delete local avatar', 'simple-local-avatars') . '<br />
							<span class="description">' . __('Replace the local avatar by uploading a new avatar, or erase the local avatar (falling back to a gravatar) by checking the delete option.', 'simple-local-avatars') . '</span>';
					} else {
						if (empty($profileuser->simple_local_avatar))
							echo '<span class="description">' . __('No local avatar is set. Set up your avatar at Gravatar.com.', 'simple-local-avatars') . '</span>';
						else
							echo '<span class="description">' . __('You do not have media management permissions. To change your local avatar, contact the blog administrator.', 'simple-local-avatars') . '</span>';
					}
					?>
				</td>
			</tr>
		</table>
		<script type="text/javascript">var form=document.getElementById('your-profile');form.encoding='multipart/form-data';form.setAttribute('enctype','multipart/form-data');</script>
		<?php
	}

	function edit_user_profile_update($user_id) {
		if (!wp_verify_nonce($_POST['_simple_local_avatar_nonce'], 'simple_local_avatar_nonce'))
			return;
		if (!empty($_FILES['simple-local-avatar']['name'])) {
			$mimes = array(
				'jpg|jpeg|jpe' => 'image/jpeg',
				'gif' => 'image/gif',
				'png' => 'image/png',
				'bmp' => 'image/bmp',
				'tif|tiff' => 'image/tiff'
			);
			$avatar = wp_handle_upload($_FILES['simple-local-avatar'], array('mimes' => $mimes, 'test_form' => false));
			if (empty($avatar['file'])) {
				switch ($avatar['error']) {
					case 'File type does not meet security guidelines. Try another.':
						add_action('user_profile_update_errors', create_function('$a', '$a->add("avatar_error",__("Please upload a valid image file for the avatar.","simple-local-avatars"));'));
						break;
					default:
						add_action('user_profile_update_errors', create_function('$a', '$a->add("avatar_error","<strong>".__("There was an error uploading the avatar:","simple-local-avatars")."</strong> ' . esc_attr($avatar['error']) . '");'));
				}
				return;
			}
			$this->avatar_delete($user_id);
			update_user_meta($user_id, 'simple_local_avatar', array('full' => $avatar['url']));
		} elseif (isset($_POST['simple-local-avatar-erase']) && $_POST['simple-local-avatar-erase'] == 1)
			$this->avatar_delete($user_id);
	}

	function avatar_defaults($avatar_defaults) {
		remove_action('get_avatar', array($this, 'get_avatar'));
		return $avatar_defaults;
	}

	function avatar_delete($user_id) {
		$old_avatars = get_user_meta($user_id, 'simple_local_avatar', true);
		$upload_path = wp_upload_dir();
		if (is_array($old_avatars)) {
			foreach ($old_avatars as $old_avatar) {
				$old_avatar_path = str_replace($upload_path['baseurl'], $upload_path['basedir'], $old_avatar);
				@unlink($old_avatar_path);
			}
		}
		delete_user_meta($user_id, 'simple_local_avatar');
	}
}
$simple_local_avatars = new simple_local_avatars;

if (!function_exists('get_simple_local_avatar')):
	function get_simple_local_avatar($id_or_email, $size = '80', $default = '', $alt = false) {
		global $simple_local_avatars;
		return $simple_local_avatars->get_avatar('', $id_or_email, $size, $default, $alt);
	}
endif;

register_uninstall_hook(__FILE__, 'simple_local_avatars_uninstall');

function simple_local_avatars_uninstall() {
	$simple_local_avatars = new simple_local_avatars;
	$users = get_users_of_blog();
	foreach ($users as $user)
		$simple_local_avatars->avatar_delete($user->user_id);
	delete_option('simple_local_avatars_caps');
}

This removes Gravatar.com completely (even though the admin menu remains) AND defaults a local hosted image when no local avatar is selected.

function bp_remove_gravatar ($image, $params, $item_id, $avatar_dir, $css_id, $html_width, $html_height, $avatar_folder_url, $avatar_folder_dir) {

	$default = get_stylesheet_directory_uri() .'/images/avatar.png';

	if( $image && strpos( $image, "gravatar.com" ) ){ 

		return '<img src="' . $default . '" alt="avatar" class="avatar" ' . $html_width . $html_height . ' />';
	} else {
		return $image;

	}

}
add_filter('bp_core_fetch_avatar', 'bp_remove_gravatar', 1, 9 );

function remove_gravatar ($avatar, $id_or_email, $size, $default, $alt) {

	$default = get_stylesheet_directory_uri() .'/images/avatar.png';
	return "<img alt='{$alt}' src='{$default}' class='avatar avatar-{$size} photo avatar-default' height='{$size}' width='{$size}' />";
}

add_filter('get_avatar', 'remove_gravatar', 1, 5);

function bp_remove_signup_gravatar ($image) {

	$default = get_stylesheet_directory_uri() .'/images/avatar.png';

	if( $image && strpos( $image, "gravatar.com" ) ){ 

		return '<img src="' . $default . '" alt="avatar" class="avatar" width="60" height="60" />';
	} else {
		return $image;
	}

}
add_filter('bp_get_signup_avatar', 'bp_remove_signup_gravatar', 1, 1 );