Maintenance will run "extended" tomorrow for all U.S. realms until 11:00 a.m. PST / 2:00 p.m. EST. The last few weeks we've seen the down time grow as Blizzard's worked out issues, so I wouldn't count on the servers being up at 11:00 a.m. PST. However I'll happily eat my words. However unlike Alex, I will not eat my hat.
We also have heard a couple sources whispering in our ear that patch 3.0.8 will be dropping either tomorrow or next week. We'll have to wait and see on that one. Don't take what we're saying here as any more than a creditable rumor.
However these rumors do have some added credence in that they coincide with comments from Ghostcrawler today such as "These [changes] will be in the next patch (3.0.8) even thought they were not on the PTR," and "We'll be able to share patch notes soon."
No matter if 3.0.8 drops tomorrow or not, there will be downtime. Fable II anyone?