bbPress.org

Here is a temporary solution:

rss.php: http://llbb.pastebin.com/f5c1a8a37

rss2.php of template: http://llbb.pastebin.com/f24cd6fd3

If you need the last post content of each topic, please find a recent topic Excerpt and combine this with it.

Edit: Oops… just find out you are also the starter of that topic.