Search bbPress is a plugin by Stephen Carroll that brings seamless, unified search results from bbPress 2.0 to WordPress and fixes the bbPress login widget in all languages.
Search bbPress extends WordPress’ native search to include bbPress post types allowing WordPress to automatically include bbPress content in results. Link adjustments are made to results to ensure users will be taken directly to replies, topics, and forums. This plugin also fixes the double quote typo in bbPress’ unified login widget.
Download: http://wordpress.org/extend/plugins/search-bbpress/