Dunno if this has reached the us yet, but I'm having the issue now here in the u.k. I've seen this happen before, when diablo 3 was launched, so looks like its making a return with the latest patch.
its pretty much this, I got dced from wow earlier today, and when trying to log back in it began to load the update tool, got to the wow launcher and stopped at 70%.
I've tried several things, running wow as administrator, and my friend showing me how to delete the battle.net folder, but it didn't change anything.
Anyone else?