Well, it's case is hot - doesn't seem appreciably hotter than my PowerBook G4, though. This machine is a loaner machine - I asked before I installed it if it would cause a problem and he indicated no. I am however carefull to give it plenty of air circulation. When I set it on the desk, it actually sits on a couple of pencils to allow air to circulate under the machine. I've heard some people use a wire cake cooking rack - anything should help if it allows air to circulate. I haven't found a Temperature Monitor widget yet for the MacBookPro, so I don't know what the indicated internal temps are...
When I buy one of these for myself, I'll also buy Apple's service contract, just in case I do fry the CPU or something else.
beadman