Launching simultaneously on Xbox 360, PC and Mac, and on PS3, Counter-Strike: Global Offensive has been slated for August 21. CS: GO will be sold for 1200 MS Points – $15 on platforms that aren't called Xbox 360.
Source: http://www.joystiq.com/2012/06/04/counter-strike-global-offensive-is-go-for-august-21-launch/