I asked an ebay seller for his thoughts about the last generation core duo Macbook Pros and the newer i5s (15″) and i7s (17″), “I’d stay away from the newer MPB models until Apple solves the heating issue . . . previous models (of the Macbook Pro), such as the 2.8 Ghz MBP run barely warm to the touch and will last a lot longer because of that.”
Wanting to know exactly how hot would be too hot for the processor temp to rise up to I did some searching on the topic and came up with several references to the heating issue: