That "window groups" seems really interesting, as does the hor/vert maximization. I don't know if I've ever seen that before. The groups in particular seems really nice: that would almost serve to do away with apps like Coda (which I use to program on the Mac, and which advertises a one-window everything device), at least for the sake of getting things done for cheap.
The virtual desktop isolation makes a lot of sense. Thanks for the clarification! I agree: it would be really nice to have an option for completely separating the spaces from one another. Chalk that up as another thing I didn't know Gnome could do.
Sorry my del.icio.us program didn't work. What fails with it? I'm curious, since it advertises indexing directly. You could try importing your bookmarks as Safari bookmarks, then opening them up like that? Though I don't think Spotlight handles bookmarks very well. I know Google Bookmarks get indexed, but handling two bookmarks sites isn't optimal.