Oh I see your point. For some reason I thought blizzard never does open beta's. They are always by invite. I might be wrong, but it's how I got into MoP, Diablo, etc
Right now the closed beta is happening. You need an invite or win a beta key competition to enter that. The open beta (where you do not need an invite to play) is coming in December so I read. That date is always subject to change.