I went to log in- the launcher started downloading an update- a quick check of the WoW General Forums didn't reveal much, but this...

people who have applied the patch cannot log into the game.

You can bypass installing the patch by running wow.exe directly from the WoW folder rather than running the launcher.

At least until there is more information...

Update:

Bypass doesn't seem to work for everyone.

Also, blue post on Tech Support forum acknowledges that some people are having login issues associated with this patch and they are working on it.

Still no blue post about what exactly this is, however.

Wow.com's not-very-informative but kinda funny post:

I and many tipsters have encountered some issues tonight when trying to launch the game.

Here's what we know:

* The Launcher is downloading something small.
* It is taking much longer than the 2 minutes estimated.
* Sometimes the download fails.
* Once the "something" has been downloaded, some are getting "unable to validate game version".
* Constant attempts to log in appear to make the error go away.
* There is no indication of what has been downloaded.

Here's what we don't know: What was downloaded.

We will update you as soon as we know anything.

Please note: There is no indication patch 3.3 is dropping. NONE.

I can't log in because it's not downloading, not installing and telling me it needs the update. Gah!

The computer system at work stopped letting everyone access their files too today. Bad day for the digital world I guess.

Latest update from Bliz:

http://forums.worldofwarcraft.com/thread.html?topicId=20860801510&sid=1&pageNo=5#96

Apparently it should be fixed now, and if you're still having trouble you should follow the instructions in the link above.