Index: capabilities.php
===================================================================
--- capabilities.php	(revision 30972)
+++ capabilities.php	(working copy)
@@ -1072,7 +1072,7 @@
 		break;
 	case 'delete_post':
 	case 'delete_page':
-		$post = get_post( $args[0] );
+		$post = isset( $args[0] ) ? get_post( $args[0] ) : get_post();
 
 		if ( 'revision' == $post->post_type ) {
 			$post = get_post( $post->post_parent );
@@ -1116,7 +1116,7 @@
 		// edit_others_posts
 	case 'edit_post':
 	case 'edit_page':
-		$post = get_post( $args[0] );
+		$post = isset( $args[0] ) ? get_post( $args[0] ) : get_post();
 		if ( empty( $post ) )
 			break;
 
@@ -1160,7 +1160,7 @@
 		break;
 	case 'read_post':
 	case 'read_page':
-		$post = get_post( $args[0] );
+		$post = isset( $args[0] ) ? get_post( $args[0] ) : get_post();
 
 		if ( 'revision' == $post->post_type ) {
 			$post = get_post( $post->post_parent );
@@ -1191,7 +1191,7 @@
 		}
 		break;
 	case 'publish_post':
-		$post = get_post( $args[0] );
+		$post = isset( $args[0] ) ? get_post( $args[0] ) : get_post();
 		$post_type = get_post_type_object( $post->post_type );
 
 		$caps[] = $post_type->cap->publish_posts;
@@ -1199,7 +1199,7 @@
 	case 'edit_post_meta':
 	case 'delete_post_meta':
 	case 'add_post_meta':
-		$post = get_post( $args[0] );
+		$post = isset( $args[0] ) ? get_post( $args[0] ) : get_post();
 		$caps = map_meta_cap( 'edit_post', $user_id, $post->ID );
 
 		$meta_key = isset( $args[ 1 ] ) ? $args[ 1 ] : false;