my mom was visiting recently and the fact that the "show desktop" feature activates simply by moving your mouse to the bottom right of the screen freaked her out when all the windows all of a sudden went translucent.

Win7 does this as well, unless you've turned it off. Right click the little "chiclet" and you can enable/disable the Aero Peek feature. Clicking it will minimize all windows to show the desktop. Click it a second time and the windows restore back to their original sizes/location.

awesome!!!!