Keyboard Command to Sleep in Lion

Power Button > Tab > Return

If you used to choose the Sleep option with TAB key after hitting the POWER button on your Mac, Lion may have your muscle memory befuddled. Never fear, there is a better way: just hit the “s” key after the POWER button, and that Sleep button will get selected without the TAB key two-step.

Additional tip, if you wish to invoke the POWER button from an Apple Keyboard, use Ctrl+Eject.