To catch you guys up, a little bit ago I had a bunch of heat problems with my MacBook, I took it in and got it checked. They cleaned it and said it was filthy inside. They put it back together and ran a hardware diagnostic and nothing was wrong. I got it back and it worked a lot better but it was still rough around the edges. I ****ed around with Ubuntu a bit and ultimately erased the harddrive and did brand new install of Tiger (still don't have Leopard). Now, after a about a month, I have my computer set up the way I like it again.
My point is this - now my computer runs 60 F degrees cooler! At the time, my 'Book just under a year old, and I normally use it at my desk and don't often take anywhere. If you have an MB or an MBP, get it cleaned at least once a year.