We've had some serious maintenance in the last few weeks, and it looks like they've come to an end. The extended maintenance that's been going on has been to fix the much hyped "Additional instances cannot be launched" error, and by all accounts the bug has been fixed. But let's not kid ourselves, there'll be at least a dozen comments claiming differently after this post goes up. But it's all good, because eventually the cross-server instances are going to take care of that problem entirely.
The maintenance tomorrow will run from 3:00 a.m. PDT / 6:00 a.m. EDT until 11:00 a.m. PDT / 2:00 p.m. EDT.
Since WoW will be down, I recommend checking out Champions Online if you haven't already. It's a nice comic book MMO that has some real potential. One thing I really enjoy about it is that its graphics are not super amazing -- they look like comic book graphics. In that sense, it's a very immersive graphical experience.
Kyle Horner of our sister site Massively wrote the WoW player's Guide to Champions Online. Check it out for more information about a nice game you can play during WoW's downtime.