For those unfamiliar with OnLive, the service allows people to play games over an internet connection without having to own an Xbox 360, a PS3, or a PC that required selling their firstborn. The service sounds pretty swell, and I would try it myself if I didn't live in Canada where we get our internet through strings and plastic cups.
So why did GameStop do this? Because OnLive is a "competing service." It not only competes with their physical stores, but also with the recently purchased, popup laden, Impulse, a digital download service that also has not much to do with OnLive. It also competes with a service similar to OnLive that they plan to launch some time in 2012, which may or may not actually feature Human Revolution.
After customers became rightfully pissed off, GameStop decided to make it up to them by taking their ball and going home, sending all copies of HuRev back to publisher Square Enix. To GameStop's credit, you will supposedly be allowed to return your pre-opened copy if you kept the receipt, but if you attempt to do this I recommend leaving the rest of the day open and bringing along some manner of torture device.