StarCraft 2 Beta Downloading Has Begun

Starcaft 2 Beta has begun, it appears that waves of invite emails are being sent out. As of right now select players are downloading the installer. It is not clear what exact groups are receiving the invites, whether it be beta opt-in, BlizzCon, or other contest keys. It is being advised that you login to your battle.net account and check your managed games for SC2 Beta.

Screenshot of the install screen: