Index: wp-includes/post.php
===================================================================
--- wp-includes/post.php	(revision 22002)
+++ wp-includes/post.php	(working copy)
@@ -1296,6 +1296,8 @@
 		'edit_others_posts'  => 'edit_others_'  . $plural_base,
 		'publish_posts'      => 'publish_'      . $plural_base,
 		'read_private_posts' => 'read_private_' . $plural_base,
+		// Post creation capability simply maps to edit_posts by default:
+		'create_posts'       => 'edit_'         . $plural_base,
 	);
 
 	// Primitive capabilities used within map_meta_cap():
Index: wp-includes/capabilities.php
===================================================================
--- wp-includes/capabilities.php	(revision 22002)
+++ wp-includes/capabilities.php	(working copy)
@@ -1046,6 +1046,18 @@
 				$caps[] = $post_type->cap->delete_private_posts;
 		}
 		break;
+	// current_user_can( 'create_posts', $post_type )
+	case 'create_post':
+	case 'create_posts':
+		$post_type = isset( $args[0] ) ? $args[0] : 'post';
+		$post_type_object = get_post_type_object( $post_type );
+
+		if ( isset( $post_type_object->cap->create_posts ) )
+			$caps[] = $post_type_object->cap->create_posts;
+		else
+			$caps[] = $post_type_object->cap->edit_posts;
+
+		break;
 		// edit_post breaks down to edit_posts, edit_published_posts, or
 		// edit_others_posts
 	case 'edit_post':