Blizzard posted an announcement that the servers would be down most of today, for unspecified purposes.
We will be performing scheduled maintenance beginning on Saturday, February 18th, at 10:00 AM PST and we expect the service to be available again at approximately 6:00 PM PST. During this time the Battle.net servers and any online games will be unavailable for play.
You’ll note a lack of anything like, “we’ll be installing beta patch 13 during this time” in this update. You’d assume it’s part of the whole thing, and that the servers wouldn’t come back up for a few hours, then go down again for the patch, but who really knows?
Thanks to metarox in comments for pointing to another thread, in which Vasadan breaks Bliz CM format and provides a straight answer to a question:
We are shooting for later tonight, but we don’t have any solid ETAs. I would keep an eye on the General Discussion and Beta Feedback forums for updates as that is where the status updates will be 🙂
Just as a brief update, the maintenance has been extended to 8 pm PST.
We’ll do our best to keep everyone updated as we go.