For whatever reason, Mission Control was acting strange and not correctly showing my desktops.
Mission Control is apparently still tied to the Dock process. So to restart it go to Terminal and type:
killall Dock
As with previous OS X version, this will restart the Dock and Expose/Mission Control. This isn't really a new hint. More of a confirmation that this technique still works in Lion.
[crarko adds: No, not new or earthshaking. But sometimes it's comforting to know that old techniques are still applicable to new features.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20110802073945173