The promotion's website at skysurprise.com has not yet updated to let you sign up... but that's ok. T-Mobile has updated their home page to include a link to the sign up page... and the best part is, there's no credit card required! All you need is a name, e-mail address, username and password, and you're done.
Sweeeeet! I've got a new office for the next three months... woo hoo!