Found this, but it really should be in WordPress Core:
// Body class for admin
// http://www.kevinleary.net/customizing-wordpress-admin-css-javascript/
function base_admin_body_class( $classes )
{
// Current action
if ( is_admin() && isset($_GET['action']) ) {
$classes .= 'action-'.$_GET['action'];
}
// Current post ID
if ( is_admin() && isset($_GET['post']) ) {
$classes .= ' ';
$classes .= 'post-'.$_GET['post'];
}
// New post type & listing page
if ( isset($_GET['post_type']) ) $post_type = $_GET['post_type'];
if ( isset($post_type) ) {
$classes .= ' ';
$classes .= 'post-type-'.$post_type;
}
// Editting a post type
$post_query = $_GET['post'];
if ( isset($post_query) ) {
$current_post_edit = get_post($post_query);
$current_post_type = $current_post_edit->post_type;
if ( !empty($current_post_type) ) {
$classes .= ' ';
$classes .= 'post-type-'.$current_post_type;
}
}
// Return the $classes array
return $classes;
}
add_filter('admin_body_class', 'base_admin_body_class');