http://games.yahoo.com/blogs/plugged-in/gamestop-under-fire-removing-free-coupons-deus-ex-234821510.html
Apparently they don't like OnLive, even though every copy comes with the coupon. According to the article they want to "protect their digital distribution system". You mean, the one you bought from Stardock at less than it was worth, and never going to fully use.
One, this is a horrible thing for Gamestop to do, and two: Stardock, why did you sell Impulse to Gamestop? It was so awesome, and so much better than Steam...