First, I invite you to look at the new "Spaces". This feature has been standard in GNOME, KDE, and Xfce for years. I even had multiple desktops on Windows XP in 2003, thanks to the nVIDIA software that came with my HP Pavilion a320n. I would normally give Apple kudos for making it look better, but that had already been taken care of by Compiz.
Examples of GNOME's default Workspaces:
Second, take a look at the "Stacks." The default GNOME Panel has a nifty applet called a drawer, which allows the user to put other applets, shotcuts, and what have you into a collapsible container. Sound familiar? However, this is one idea with which Apple was able to make significant aesthetic improvement.
Examples of the GNOME Drawer (with links to my documents, music, and photos):
Stuff that you can add to the Drawer (the Custom Application Launcher allows you to add virtually anything):
