Via FT:

For stays through April 25, 2009, eligible American Express Platinum and Centurion cardholders can receive up to two free nights at either the Encore or Wynn Resort in Las Vegas. There is no minimum stay requirement. All FHR amenities, such as room upgrades, food vouchers, etc. do apply, but tax and fees are not included. There are a number of blackout dates, but weekends are available.

To book this offer, call Platinum Travel Services at 1-800-443-7672 and tell them you heard about this promo.