The StarCraft 2: Heart of the Swarm beta has gone live.
The beta is currently only open to a select group of "pro-gamers, members of the press, Arcade contest winners, and shoutcasters", but there's no NDA, so if you're not already playing it you should certainly be able to watch a live stream to calm the anxious twitching.
Blizzard says it'll be adding more players to the beta soon, so make sure you've 'opted in' for beta trials by clicking on the 'Beta Profile Settings' under the Account Management section of your Battle.net account.
Opting in doesn't guarantee access, but here's the basis on which testers are picked: "Beta testers are chosen according to their system specifications and other factors, including recent StarCraft II activity (and an element of luck), when selecting individuals during each round of invitations. Our goal is to have a wide variety of players and system types," explains Blizzard.
The beta focuses on multiplayer gameplay, you don't need to own StarCraft 2 (although it'll improve your chances of access) and there's currently no set ending date.
Head through to the official site for more details.