If you check their forums, you will see alot of bitterness and resentment amongst the phpbb2 members against some guy who started a pn+phpbb2 conversion project on SF.
Here is my conclusion::
We NEED to get phpbb2 integrated into postnuke. Currently, we have several message forum systems but nothing that is up to the standard of phpbb2. In order to develop a complete community portal, strong forums are necessary. The forum systems available to postnuke at this stage simply dont have anywhere near the development time that phpbb2 has into it.
I have minimal coding skills, but would love to help out or organize an effort to convince the phpbb2 guys to at least consider forming a positive relationship with the postnuke community that would benefit both parties. THEN begin a project to provide means to merge the two.