Mine was recently hacked, too...
I just experienced a similar hack. I was playing Saturday night with my only character, a 62 blood elf hunter. I'd been working on leveling up my herbalism, alchemy, and fishing and got disconnected a couple times but thought nothing of it. I stopped playing around 11:00 pm (what can I say - I'm old), and when I checked my email the next morning I had three emails from Blizzard. The first was a notification that my WoW password had been changed, the second was a notification of a password reset, and the third was a notice that my account had been suspended for 72 hours due to unauthorized software that gave me an unfair advantage. I send them an email explaining the situation, and in the mean time started googling around to see what I could learn about WoW accounts getting hacked. I just this morning got my account re-activated and have changed my password, there there's a WoW update so I haven't been able to get into the game to see what the situation with my hunter is.
After reading the various threads about this on the WoW forums and other places I've seen repeated speculation that much of this account hacking is due to keystroke loggers. While that could be an issue for some hacking, I doubt that's what happened in my situation. Partly this is because I play WoW on a Mac, but the most compelling piece of evidence is that whoever hacked my account requested a password reset to my account. This seems odd to me for a couple reasons. First, they had already changed my password, so there would be no reason for them to reset it, especially since that reset notification gets sent to me. The more suspicious aspect of this however is that in order to request a password reset you have to know the answer to a security question. In my case, that security question was set up a couple years ago when I first created my WoW account and I have *never* used it in WoW or anywhere else. Also, that question and answer text (even just the answer text, which is exceptionally obscure) appear *nowhere* on any of my computers. This was absolutely not a case of keylogging - there has to be some other security weakness in the WoW system, perhaps akin to an SQL database issue or something, since I know other web sites have had issues with that in the past.
I see that the WoW update has just now finished, so I'm going to check on my hunter and see how bad things are, but I thought I'd share my experience as another data point.