Don't look now bro's but it looks like battle.net has been updated.
I was getting the same error on the Live forums - I was clicking Login and wasn't getting logged in.
Went cleared my cookies then tried logging on battle.net. I'm now able to logon just fine.
You might just need to clear your cookies and log on the new battle.net
About to check logging on the Cata forums now
PS details on the new battle.net at
http://www.wowinterface.com/forums/s...d.php?p=199269
UPDATE : Tried logging on the Cata beta forums. Got a server error this time. Might need to wait till they have all the battle.net stuff back up.