We've been playing with Snow Leopard 10A402 for a few hours. Here's a running list of what we've found:
Definite snappieness™ all around. Shut down takes 5 seconds. Startup significantly faster as well. This isn't one of those "I think it is faster". IT is more like "Dayum!"
Exposé on multiple monitors is fixed.
Battery life says about 30% longer (no time to put into practice - yet)
In the Dock, you now get menus like right and below.
New version of Quicktime