To enter, you'll need to collect tokens. You can get tokens by logging in daily and by doing various things on the website like watching videos, referring friends, visiting pages, and more.
Right now, you can start collecting tokens, but you can't start entering to win until May 29th, 2009. It's a good idea to start entering early, though, so that you can get as many tokens as possible when the prizes start being given away.
And there will be tons of prizes to win. Every 15 minutes from May 29th until August 20, 2009, a new winner will be chosen.
The grand prizes are trips to BlizzCon, Blizzard's convention, worth $3,000. Other winners will receive laptops, desktop speakers, gaming keyboards and mice, WOW swag, and much more.
Entry is open to US residents aged 13 and above. Enter once per token until August 20, 2009.