A bit of a black eye for Amex and Travelocity on this one.  A class action lawsuit accuses them of colluding to charge more for trips when American Express gift cards are used to pay for them than they would otherwise.

Named plaintiff Morris Wilner said he received a $200 American Express prepaid gift car for signing up with Verizon for telecommunications services. He said he discovered the pricing scheme when he tried to use the card to pay for a trip.
Wilner said he visited American Express’s Web site, and was directed to Travelocity’s Awards site, where, using the gift card, he paid $35 more for airline tickets than he would have had he paid through other means.