Since I'm not Apple-savvy, do you mind explaining the difference, Camel? My friend (who isn't partial to any platform) says it's virtual desktops and nothing more. :\
Edit --
So I watched a video of Steve Jobs demoing spaces. While I see a few things there that I haven't seen in the Linux virtual desktop implementations I'm familiar with (and I don't make heavy use of virtual desktops, so I don't know much about them), I still think it is a marginally fancier virtual desktop implementation.