BuddyPress.org

Also, try it on testbp.org – it has been working really well and I receive @messages all the time, each with an active reply stream.

This is never going to work like a message posting wall, it’s simply not how an activity stream works. If that’s what you want/need then stick with the old wire. Please give this new functionality a chance though, it works quite well if you take time to use it in an active environment.