defaults write com.apple.Dock workspaces-auto-swoosh -bool NO killall Doc
This will make Command-Tab only switch between applications running in the same Space. However, if you switch to an Application which is not in your current Space, it will
still warp you to the Space where it is not warp you between spaces; you much always switch spaces manually. Regardless, it's much better and makes Spaces much more usable. Though, Workspaces in Gnome still feel much better.