First:
One of my biggest problems is people writing me who forgot what their forum "name" was and what their password is. Before they can get phpBB to send them a new password I have to help them find their account name!
How hard would it be to make people start logging in with their email address and password as opposed to their phpBB username? They'd still get to post with their "username" in the forums, but this way everytime they login its their email address, and if they forgot their password, they just put in their email address and it emails them a reminder. Thoughts?
Second:
phpBB3 will sooner or later become stable. Have you looked at the changes in phpBB3 yet to see how hard it'll be for the connector to work with phpBB3?
Finally: This is awesome. I hate the fact that I am going to have to move my forums from their own unique domain under the domain I use for my joomla site, but this is now worth it. One of the benefits of this is going to be getting rid of "robots" that register fake accounts.
Great mod guys. I hope you keep up with it and/or get the Joomla folks to consider integrating this functionality into Joomla itself. It just makes sense.