According to the Windows Blog, Windows 7 is going to be “generally available” on October 22, 2009. Of course you might be able to snag up a copy of it sooner, especially with a MSDN subscription, or if you attend a launch event (I’m assuming they are going to give away a copy at the launch events – they have in the past) No word on pricing yet.
Of course, the Release Candidate is already out there, if you want to start getting your hands dirty!
Related posts:
Microsoft DPM
MicrosoftExchange
Nerd with a .45
PowerShell