The following section contains information from a previous version of StarCraft II which is no longer valid.
The new version of battle.net launched on March 19, 2009. It offered a beta opt-in.
As of May 6, 2009 the beta opt-in page had been updated. Beta candidates could download a program which will scan their system and determine if it's capable of dealing with StarCraft II beta. As of May 27th European users were able to opt-in.