Theymos wants the new forum software tested for security flaws. I think this is the primary hold up.

I happen to like this version just the way it is, without many changes to the look and feel and function of it.  However, I do find it very odd that this thing has been strung along for so many years without an explanation as to why that's the case (or at least I've never heard one, but I'll confess that I have the New Forum Software subsection on ignore, so I could be missing one if it exists).