This plugin adds creates a whitelist of shortcode tags that can be applied to comments, bbPress and BuddyPress.
This plugin is designed to safely allow bbcode shortcodes and other safe shortcodes to be embedded in bbpress topics and replies and also blog comments. You don't wan't users entering shortcodes such as [bbp-login] in the middle of their reply.
It doesn't actually implement the shortcodes though, for that you need a separate plugin. I recommend my own bbPress2 BBCode plugin, as this is fully whitelist aware, in that it also parses the contents of the shortcodes, so [b][bbp-login][/b] also gets parsed for safety. Something that doesn't happen with non whitelist aware shortcode plugins.