Today many fans from around the globe have reported receiving StarCraft II Beta keys from opt-ins as well as event keys. The third wave has started, and is likely to go on throughout the day, and perhaps even into the weekend. Waves seems to be arriving every one to one and a half weeks (since last wave was Tuesday last week), which is pretty good.
Some people have unfortunately had problems with their beta keys. They either received a key by mail that does not work, or the game is added to their account but they can't log in.
A Solution is on the way, says Blizzard.