Since upgrading my Late 2010 MacBook Pro to OS X Lion, I noticed that swiping my finger across the trackpad no longer wakes it from sleep mode. Clicking the trackpad or pressing a key on the keyboard does still wake it up as expected.
I can't seem to find any related options in System Preferences, so is there another way to re-enable this feature?
No, I'm afraid Apple has removed this functionality from OS X Lion. Clicking the trackpad or pressing a key on the keyboard is now the only way to wake your Mac from sleep.
Keyboard presses and mouse button clicks can wake a sleeping computer. Mouse movement alone will only wake a sleeping display.
This is actually a feature to prevent accidental movements of the mouse or trackpad effect your Mac from waking up to easily.
For me this was a great feature because i use an external monitor with my macbook. If i had my macbook lid closed but forgot my mouse on, a slight movement of my desk would cause my macbook to wake up, but since the lid was closed only the external monitor would work until i go into display settings and click "detect displays". this was really annoying because all the windows that were on my MacBooks screen before would be moved over to my main monitor and get thrown all over the place.
