i got my mbp dec 09 and i noticed it started heating up after 2 months into using it.. another 2 months later, i got a usb plug-in cooling fan. now it doesn't heat up at all. you're not suppose to leave your mbp on any surface that block it from radiating out the heat. because mbp's dont have a fan like other laptops like hp or sony or etc, u hav to type on cooler surfaces.. it uses its outer aluminium shell to emit heat. plus, if u let ur laptop continue to heat up without attending to it, it shortens the lifespan of ur laptop.
BS! There is a cooling fan, and you can put the MBP down on any surface as long as the display hinge opening where the vents are are not blocked. If you actually remove the bottom aluminum cover, the fan sucks more air, and the computer stays 15 degress Farenhight cooler. The problem is, is that exposes the logic board and all the other fragile things inside. BTW How would the aluminum emit the heat? The aluminum heats up, and I don't have anything to cool the aluminum.
Sorry buddy. Please check your facts before posting. Also, why did you waste money on a cooling fan? As long as the CPU doesn't go past 105C/221F, there is nothing to worry about.