I just got a modification of the terms of cardmember agreement for one of my Amex cards.
In there under "eligible purchase exclusions" it says, "effective April 2nd, we are amending the agreement regarding the accumulation of reward points (or miles) appended to your agreement by adding the following to the end of the sentence defining eligible purchases: "or the purchase of American Express Travelers Cheques and American Express Gift Cheques or other cash equivalents"