“Pay off your entire balance between March 1, 2009 and April 30,
2009, and we will send you a $300 value prepaid card1 to thank
you2. Enrolling in this promotion will automatically cancel your
account.”

link to AmEx offer page.

This offer is not available to all American Express cardholders,
and the verification code is being delivered by mail.

CreditMattersBlog.com

If you receive the offer, enroll by February 28, and pay off your
account balance in full before April 30, 2009. they promise to send
you a $300 pre-paid AmEx card.