I'd stick with vBulletin - everyone knows it (if they've used other forums before, it's hugely popular and there's probably a good reason for that).

If possible, make this the new MeeGo forum: create a Maemo sub-section, which might become a "Nokia devices" section within MeeGo in future. All existing members can participate in the MeeGo sections as and when it becomes relevant to them.

Since there is going to be some sort of compatibility between the next OS (aka MeeGo) and the existing Maemo5, it makes no sense to split the communities when there is so much potential overlap.

t.m.o. has almost 30,000 registered members, how many Moblin forum members are there? On numbers alone, this community surely dominates and should continue with as little disturbance as possible on meego.com