While I'm a fan of Apples (no more than Vista though), I'll admit their laptops are pretty crap when it comes to overheating.
I've got a G3 iBook that has a permanent red line about 1" long on the screen, because that model has a problem where the GPU overheats to the point it desolders some of it's connections to the motherboard.
A friend of mine with a G4 powerbook managed to fry his RAM and probably a few other things on the motherboard, so the computer just became really unreliable, and could take dozens of attempts just to get the thing to start up. It probably overheated because he always used it sat on top of it's neoprene cover, with the vents at the back partly blocked.
My first Macbook Pro was hot enough to burn you if used as a 'laptop' (Apple stop using the term because they were so hot). Luckily it got nicked, so I got a free upgrade to the next generation ones, thanks to new-for-old insurance.
That new Macbook Pro is a lot better in that you can actually use the thing as a laptop for things like web surfing, but it still had the motherboard fry itself, when I shut the lid and because of a firmware bug it came out of standby, while it couldn't get anyairflow, the lid being closed. Thankfully it was under warranty, as a new motherboard would have cost 1/4 of the original price.
Basically Apple have f***ed up by designing their cooling to fit into the nicely designed cases, without spoiling the design, and limiting it to be as quiet as possible.
I've worked on Mac desktops from the old beige plastic pieces of s*** up to the G3/4 Powermacs (awesome cases for modding, stuffed a PC in one, made another an 8 drive file server. Both my parents have one, as I got sick of fixing their Windows problems), and every single one of the things had a p*** poor cooling solution, not helped by the fact most Mac users never open the cases and clean the dust out of them.
In many ways they're damn good computers, with some good design ideas, but they sacrifice far too much to make them look good.
If you're using a Mac laptop always keep the firmware up to date. Get any toolbar addons you can that will let you crank the fans up to full speed, because the default settings are nowhere near good enough (this is especially the case if you're running Windows, as the Apple provided drivers for it are useless at managing the power usage or controlling the fans properly).
Get the thing a laptop cooler to sit on, or at least raise it up to get some airflow underneath, and never sit it on anything that insulates heat in any way (like on the covers while sat in bed).
You can run WoW on an Apple Laptop, but to stop it crashing from overheating, you'll need to provide extra cooling, as even at full blast the internal fans can't cope with both the CPU and GPU working at load.
