Blizzard has now given an additional Beta key to those players who have already recieved one. They can use this to give to a friend so they can download and play the Beta too.

Blizzard also says they will continue the Beta Key waves since a new wave was started yesterday.

Oh and on a slightly unrelated note, Blizzard is also saying that players will only be allowed to have 1 account per copy of StarCraft II they have. This is to prevent people from starting tons of new accounts and picking on new players, wasting space, etc.