The latest targeted promo kicks in after you get ten nights under the Free Weekends promotion, and that's good till June 30. However, as Lurker indicated, he can't add people to that promotion (though others have reported success through other channels).
Other than that, I don't know of any new promotions out there... I would think Starwood is biding their time with Free Weekends (and Free Weekends Bonus) for now..