At (or around) Midnight (eastern standard time) tomorrow night (Saturday May, 19), the forum will be down while we make the move to the new software/database.
I have tried this move several times now in a sandbox environment and the import is taking about 40 minutes, reindexing runs another 15 or so and misc. configs run another 5 to 10 minutes.
In other words, we're looking at roughly an hour's worth of downtime.
When we come back up, there won't (or shouldn't be) much in the way of changes. The forum should be pretty much a direct port of the existing phpBB forum. One thing I've noticed in the trial runs is that Avatars have been problematic.
We will be sure to hang on to everybody's images, but you may not see then until we get back into the office. I'm thinking about relaxing the restrictions on avatars anyway so maybe we'll just make some new ones.
Anyway, the move is going on Saturday night around midnight and we'll be off for about an hour while it happens.