Has anyone else seen this promotion? It appeared on my promotions page, with no real details, other than "Call to find out more"

Bonus Miles Bonanza
Ticketing dates: September 1, 2010 through November 30, 2010
Travel dates: September 1, 2010 through November 30, 2010
Offer: Register, purchase and fly qualifying roundtrips on United® or United Express® by November 30, 2010, to receive up to 20,000 bonus award miles. Please see your offer email for details about how many qualifying roundtrips you need to fly, or call Mileage Plus Customer Service at 800-421-4655.