Microsoft is rewarding Xbox Live Gold subscribers with the chance to win limited prizes and Microsoft Points, which in this case is more of a chance for a discount on the subscription itself. But I suppose it's better than nothing.
They will be giving away 10 Limited Edition Kinect Star Wars Bundles (ARV $449.99 USD), 10 Xbox 360 Special Edition 4GB Kinect Family Bundles ($299.99 USD), 10 Limited Edition Mass Effect Kinects (ARV $149.99), 10 10,000 MSP prizes, 100 1,000 MSP prizes, and 500 800 MSP prizes, and 1,000 400 MSP prizes.
Your odds of winning are based on the total number of entries and how much you spend on the Xbox Live Gold subscription. Merely completing the online registration form will net you 1 entry, as well as purchasing a 1-month subscription. A 3-month subscription nets 3 entries; 12 months nets 12 entries; and 12 months of Family Gold nets 16 entries.
Setting the Gold renewal to automatic nets 5 extra entries. I don't recommend it, however, since you will likely need to jump through hoops with Microsoft Support to get your credit card information removed. Instead, I recommend mailing in an free entry form as detailed in the Official Rules, which will get you 16 entries all on its own. (Of course, I'm always suspicious that mail-in entries are simply tossed in the trash...)
Winners will be posted in a pdf here. The sweepstakes ends on July 1, 2012 at 4:59 GMT.