Wowhead has put up an announcement this afternoon that the beta key contest they were running has been cancelled. The announcement tells us that the distribution of the keys were exploited. Though there is no official word on what exactly the exploitation was, there is some unconfirmed talk about the beta keys being ebayed.
This is most unfortunate for those wishing to participate. Malgayne, the "Voice of Wowhead," does go on to say however that the remaining prizes will be given away using a different method soon. We'll get any more news up on this as soon as it becomes available.