A few weeks ago Starwood shared the details of their fall “Take Two” promotion, which will run from September 1 through December 15, 2013. Through this promotion you earn double base Starpoints on all stays without limit, and an additional 2,500 Starpoints for every five eligible nights you stay, up to 10,000 Starpoints.
Anyway, registration for the promotion has just opened and only takes a few seconds, so I highly recommend registering as soon as possible. Registration closes on October 31, 2013.
When you register you can opt-in to receive an email confirmation of registration, and the email should arrive almost instantly.