It's on. Blizzard has started the closed beta for StarCraft II: Wings of Liberty in advance of the game's launch sometime around the middle of the year. If you signed up to participate in the beta, check your Battle.net account, as the developer says that invitations have already started to go out.

Beyond testing StarCraft II gameplay, testers will get an early look at the revamped Battle.net service that will allow gamers to talk to one another across World of Warcraft realms and Blizzard's other titles. Players will also be able to purchase add-on content and other Blizzard releases via the new Battle.net.

StarCraft II will bring a completely rethought single-player experience to go with the online multiplayer. Single-player missions are organized differently and the way items and units are unlocked makes solo play much more exciting. Unfortunately, there won't be support for LAN play.

Once we get some quality time with the StarCraft II beta, we'll report back with our first impressions.