We have not yet set an exact date and time, but we will soon be performing an upgrade from vBulletin 4.0.7 to vBulletin 4.1.2.
This is a minor upgrade, but the forums will not be available for an estimated two hours during the migration process. I will post the planned date and time of the migration once it has been determined.
The migration could happen as early as this weekend.
As we continue to chip away at remaining issues from the major migration we performed a month ago when switching from vBulletin 3.7 to vBulletin 4.0.7, we've decided it makes the most sense to be addressing the remaining issues on the more recent vBulletin point release.
Michael