I'll just add my support for the sibling comments that Spaces is really awkward in comparison to workspaces/tags/whatever on all the Linux DEs I've used, including minimalist stuff like Openbox. In OS X, Spaces is just a tacked-on deal that doesn't work well with the rest of the experience, and most people don't know it exists until they accidentally trigger it with a corner or key combo. If you value multiple desktops, you'll be much better off using a Linux DE.

I run Arch Linux on my MacBook Pro, for instance. This has made at least two Mac fanboys seriously hate me.