Probably nothing, like usual.
I really hope it's an option somewhere.
Just ordered myself, will be interested to see how much of a difference that makes to the iMac. Im thinking of getting an SSD as well to make it run like a beast but im not sure how much of a difference that would make with only a 2.4ghz processor.
How do Apple usually post their software out? Simple ole Royal Mail?
It's fast and it's... fast but don't get your hopes up for GUI improvements.
The dock and the Finder are about as much as you'll notice until you've used it for a while
I just got a Remote Desktop Client update for SL via Software Update so they're already patching it..