In a recent release to OS X Lion, Apple fixed an annoying issue we’ve been putting up with since the operating system was released: not being able to re-arrange Spaces.
As of OS X Lion 10.7.2, you can now arrange Spaces within Mission Control (four-finger push forward on your trackpad) to your heart’s content.
All you need to do is click and drag to move Spaces around.
If you haven’t yet updated your operating system, click the Apple in your menu bar and select Software Update to update Lion.
Before the update, Lion arranged Spaces based on which one you had most recently used. Apparently, Apple either decided that the method was no longer logical, or that it was angering too many users.
Thanks, Apple! See below for a screenshot: