Not really. One thing you can certainly say about the PPC chips, was that they were extremely power efficient. It took Intel years to get even close. But if you're worried about it, just pop the latch and leave the display up enough so that there's a small gap for heat to escape, but not enough that the internal display turns on.
Those laptop cooling pads are typically worthless. Maybe even worse than worthless. Heat RISES, so what good is putting downward facing fans on the BOTTOM of the unit? They are a waste of time IMO. What little good they might do just isn't worth it.
I plan to use my older G4 Powerbook as my new "desktop computer" as soon as the ol' PC dies (shouldn't be long). Are there any cooling or overheating issues I should know about if I leave the Powerbook's lid closed and work solely on an external monitor? I'm planning to use a dual-fan "chill pad" under the Powerbook to help ease it into retirement on my desk. Any thoughts?
Thanks

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic