I had been familiar with the running joke that Apple notebooks are no longer marketed as “laptops” these days because they give off just too much heat for the average person’s lap to handle. I only realized it was also Apple’s position–somewhat–when I chanced upon a post on technopinoy.com citing Apple’s own MacBook Pro Care and Handling guide.
For prolonged use, place your MacBook Pro on a flat, stable surface. Do not place your MacBook Pro on your lap or other body surface for extended periods of time. Prolonged body contact can cause discomfort and potentially a burn.
I would say that this should be a normal warning with just about any other notebook computer. Any electronic device should give off some heat, after all. However, the MacBook Pro is different in that it was designed to dissipate heat through the metallic body itself. IMHO, this is not a very good design idea, especially for a computer that’s supposedly assumed as frequently being used on the user’s lap.
The second generation, the Core 2 Duo MacBook Pros, are supposed to run cooler than their first generation predecessors. But still, there is a tendency to be too hot for comfort. And I would say it would be a long time before Apple marketed their notebooks as “laptops” again.