There's always a chance they'll change it, but it's currently planned for September 7th. It's also important to note that it will be generally available...click here.
Vista RC1 is scheduled for a September release.
I received an email about beta testing some Windows Live WiFi services and a line in the email said:
"Required Hardware / Software:
Operating System - Windows XP, (Vista compatibility be added with RC1, currently scheduled for September 2006)"
Not much more than we already knew, but it's apparently not a late-August launch as some people have speculated.
Jerad from Indiana