I googled for awhile in vain before giving up and pulling it out of the class. I’m surprised this isn’t available in the codex. I’m responding here for future usefulness.
Here are the attributes that appear to be available:
$post->post_author
$post->post_date
$post->post_date_gmt
$post->post_content
$post->post_content_filtered
$post->post_title
$post->post_excerpt
$post->post_status
$post->post_type
$post->comment_status
$post->ping_status
$post->post_password
$post->post_name
$post->to_ping
$post->pinged
$post->post_modified
$post->post_modified_gmt
$post->post_parent
$post->menu_order
$post->guid
