If you want to play with this wierd glitch, create a preference file named "com.Apple.CoreGraphics.plist". Name the child "DisplayUseInvertedPolarity". Set the type to Boolean and the value to "yes". To get Aqua back to normal just change the value to "no". It gives a different look to all your applications. For some reason any screenshots I've taken with Grab.app look normal, so you can't exactly show this off very well without trying it yourself.
[Editor's note: At first, I thought this was just the "Inverted screen" effect from the Universal Access preferences panel, but it's not. Things are still in color, but they're all the polar opposite of their original colors. It's quite the interesting effect, and none of the screen capture tools will reflect the image. So I tried with a digital camera; here's a small snippet of an inverted polarity screen:

If you'd like to try this out yourself, the easiest way to create the file is to open a Terminal window and type:
defaults write com.apple.CoreGraphics \The backslash should allow you to copy and paste the above in one step, but in case it fails, it needs to be on one line. You'll have to logout and login to see the effect. To disable it, you can repeat the above with "NO" at the end, or just delete the com.apple.CoreGraphics.plist file in ~/Library -> Preferences.]
DisplayUseInvertedPolarity -bool YES

