US accounts are now able to access the beta registration from https://www.worldofwarcraft.com/account/beta-opt-in.html and opt-in for the Wrath of the Lich King beta. EU accounts saw this feature implemented a short time ago. It looks like the leak from the German Community Manager Gnorog is holding up to be true.
Remember that when you opt in, you are not guaranteed a spot, and you will likely not get an email inviting you to the beta right away. Instead your name will go into a pool of players who will then be chosen for the beta. That's why they call it opting in.
This is a good time to remain vigilant about email scams and other malicious programs that might try to get your user name, password, and other account information. Never share these with anyone other than official worldofwarcraft.com websites.
If the beta invites do start going out soon, expect us at WoW Insider to let our friends and families know what's really important this holiday weekend: bringing everyone late breaking WotLK news, all while enjoying their finely cooked BBQ food. I'll take two burgers to go with jalapeno cheese and a Corona.
Gallery: Wrath of the Lich King