Some discussion in this thread from June...
http://flyertalk.com/forum/showthread.php?p=7936964
It's one of the distinctions between Membership Rewards and Membership Rewards
First. Only Platinum and Centurion qualify, but of course it isn't really "triple" points, it's two additional points per dollar.
Gotcha. I knew I could count on you
mia! Amex spins it on the website as triple points...sneaky bas***ds