[_ck_]

1.0 apparently has a reverse post order ability built in

https://trac.bbpress.org/ticket/825

It’s not clear how to activate it without editing the core, I will have to take a look at it.

Added: apparently the reversal feature is also available in 0.9, it’s just that changing it in topic.php requires a core edit and it might break the direct-link-to-a-post ability.

Here is a thread with a mini-plugin to reverse the post order in 0.8 that might work also in 0.9 and 1.0

https://bbpress.org/forums/topic/change-post-order-question