Not sure if this should be considered a hint or just a curiosity. If you have GeekTool scripts running on your Desktop, they do not show up in Mission Control.
The trick to see them is to go into Mission Control and move to a Fullscreen app, and then you can see the GeekTool scripts while in Mission Control.
I have setup a swipe with four fingers gesture to move between Spaces and this works in Mission Control too.
Two screenshots which illustrate this are here: In Mission Control, and In Mission Control with a Fullscreen app.
[crarko adds: I haven't tested this one.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20110915230639854