* gets the current post type in the WordPress Admin
function get_current_post_type() {
  global $post, $typenow, $current_screen;

  //we have a post so we can just get the post type from that
  if ( $post && $post->post_type )
    return $post->post_type;

  //check the global $typenow - set in admin.php
  elseif( $typenow )
    return $typenow;

  //check the global $current_screen object - set in sceen.php
  elseif( $current_screen && $current_screen->post_type )
    return $current_screen->post_type;

  //lastly check the post_type querystring
  elseif( isset( $_REQUEST['post_type'] ) )
    return sanitize_key( $_REQUEST['post_type'] );

  //we do not know the post type!
  return null;


источник http://themergency.com/wordpress-tip-get-post-type-in-admin/