I am also looking/doing my my re-search on finding what my best option would be for phpbb/cms integration. My first choice would be wp-united but i realllly wanted to wait for v.9 to come out so it would work correct with phpbb 3.0.8
Other then that I found these 2 phpBB CMS's that might be worth looking at:
I installed primetime on my test server, got it running but it has a few bugs here and there and is very hard for me to figure out in the phpbb admin section. It has a lot of potential though because it is a CMS that was made straight for phpbb, i just don't know how to make it do what i want it to do.. I havent tried wp-phpbb-bridge yet, i believe it was just released the other day.
Like I said though, wp-united seems great but i don't wont to be dealing with a lot of bugs..... I have worked with WP in the past and it is very easy to accomplish things and self explanatory. With these other CMS's we might encounter a bit of a learning curve.
My 2 cents.