I ran across this tidbit in the HyperSpaces FAQ and I know I haven't seen it here before (and I'm quite the avid OSX Hints follower).
It has really sped up changing between Spaces workspaces for me (which I do probably over 100 times/day). Once you've seen the 'swoosh' animation a few hundred times, you don't really need to see it again. Please note the requirement of running 10.6.4 or later.
Here's how to disable the animation that occurs when switching between Spaces:
defaults write com.apple.dock workspaces-swoosh-animation-off -bool YES && killall Dock
defaults delete com.apple.dock workspaces-swoosh-animation-off && killall Dock
Mac OS X Hints
http://hints.macworld.com/article.php?story=20110214074550501