How can I get wp_list_pages separated by commas

Add this code to functions.php:

class Walker_Page_Comma_Separated_List extends Walker {
	var $tree_type = 'page';
	var $db_fields = array ('parent' => 'post_parent', 'id' => 'ID');
	var $separator = ', ';
	var $el_count = 1;
	function start_lvl(&$output, $depth) {
		$output .= "<p>\n";
	}
	function end_lvl(&$output, $depth) {
		$output .= "</p>\n";
	}
	function start_el( &$output, $page, $depth, $args, $current_page ) {
		$output.= ( $this->el_count > 1 ) ? $this->separator : '';
		$this->el_count++;
		extract($args, EXTR_SKIP);
		$href = get_page_link( $page->ID );
		$title = apply_filters( 'the_title', $page->post_title );
		$output .= '<a href="' . $href . '" title="' . esc_attr( $title ) . '">' . $link_before . $title . $link_after . '</a>';
	}
	function end_el( &$output, $page, $depth ) {
		$output .= '';
	}
}

and this code where you would like the list to be displayed in you theme:

$walker = new Walker_Page_Comma_Separated_List();
	wp_list_pages( array( 'title_li' => '', 'walker' => $walker ) );

Best Wishes,
-Mike

Not the OP, but just wanted to thank you for posting the code that you did –?helped me understand what Walkers are and how to use/customise them. Cheers!

Awesome, Glad to hear it!