RC1 of Windows Vista is now out on Connect - installed this yesterday and as you would expect there isnt too much difference from the Pre-RC1 build. Interestingly though the build number has rocketed up to 5600.
To couple with RC1, there are some new .NET 3.0 bits landing..
Runtime: Get it here
Windows SDK RC1: Get it here
Windows Workflow RC5: Get it here
The Orca's extensions are currently MIA..
Also it looks like the Tech Refresh for Beta 2 of Office is about to land any day :)