I know nothing that would do it straight to bbPress, but one could be written based on the WP plugins like WP-AutoBlog, FeedWordPress or another Maggie based plugin.
I think the best bet would be to great a WP blog (hidden) that populates using one of the mentioned plugins and then a bbPress plugin like bbSync or bbPress-Post to pull the entries from WP into bbPress as entries.
It would be better to create a plugin that does it automatically, but if you don’t want to re-invent the wheel, that is the only solution I can think of right now.
Trent
Can I pull from two different WP blogs into one bbPress Forum?
If they use the same user tables, sure.