Ok well, I just got an email - they've extended their offer - these CD keys will allow you to create a fully-functional account for free with access to all of expansions and stuff (I'm pretty sure)
Post here after you've used a keycode and others will know which are available:
Key: FZ9U3JC9Q8NS8U
Key: T6AEKE1AP198G7
Key: ZO4X18NP6VALXX
Key: HN5V5KKKDG1S7
Enjoy
