There is a very realistic looking e-mail being sent out saying you have been selected to beta test the Wrath of the Lich King Beta.  This is a fake.  Clicking on the link brings you to an official looking site that asks for your username and password.  Do not click on this link and do not fill out any information.  This is an attempt to steal your account information.  If you already clicked that link and filled out the form, go immediately to your account and change your password.