More details on how well your Mac will implement Snow Leopard is sent to us from Jim Hamm. He tells us, "For example, my MacBook Air will not realize any improvement from the 'OpenCL' design because it doesn't have a supported graphics chipset. This won't bother me as I don't use my 'Air' for any intensive graphics work anyway. Otherwise, it looks like my 'Air' is good to go with Snow Leopard.
"Even if your particular hardware configuration won't fully support all the features of Snow Leopard, I think you'll still realize benefits, including freeing-up about 6GB of hard drive."
Take a look at the article from About.com and note that Snow Leopard is only for Macs that use an Intel processor.