Blizzard announced on the StarCraft II site that the Beta for the game, which was to end on the 31st May, will be extended to the 7th of June in all regions.
"In order to prepare for the final phase of beta testing, we plan to extend the current phase in all regions until Monday, June 7. After this date, the beta test will be unavailable for several weeks while we make some hardware and software configuration changes for the final phase of the beta test and the release of the game. We plan to bring the beta test back online for a couple of weeks prior to the game's launch to complete our testing. We'll have more details to share about when this final phase will begin at a later date.
We'd like to thank all of our beta-test participants for your enthusiasm, dedication, and valuable feedback during the beta test, and we look forward to hearing more of your thoughts on the StarCraft II beta test as the game's July 27 launch approaches."