Option + Command + Eject works, but you must press all three keys
simultaneously. Doing a more natural Option + Command and then press Delete while holding down the two others, does not work; it just makes the computer sleep for a second or two, and does not produce a dimmer light.
Interesting.
Apple does not list this key combo in their help area list of keyboard commands--must be an Easter Egg. Looking at that list did provide some interesting commands I hadn't know about, though--for example, doing a Shift+Command+4 and then pressing the space bar will take a picture of the active window only. Holding down the Control key while selecting a Sh+Cmd+4 screen capture will save the captured image to the clipboard.
Oh, and make sure your finger doesn't slip when you do an Option + Command + Eject. If you do a CONTROL + Command + Eject, it quits all apps and shuts down the computer.