Just saw/heard the Windows Server 2008 Kernel Changes by Mark Russinovich (SEC416) from TechEd in Orlando. As always, valuable information - and hearing Mark stumble as his system unexpectedly crashes for him is kind of funny.
For those of you having 32-bit terminal services systems, you should look forward to the improvements: More virtual memory, parallel sessions initiations (e.g. logons) etc.
But, hear it all for yourself here.