We've got our hands on a very interesting piece of information about the upcoming GeForce 9800GX2 card and it looks this these cards will run hot enough to prove to be dangerous if you touch them while in use.

As you can see from the screen shot taken from the quick installation guide of the 9800GX2 card, users are warned not to touch the cooling system of the cards due to the hot surface.

The other warning message is equally interesting, it seems like you have to be careful not to squash these "cards" together, as you might damage the GPUs if you do this. So don't stack a bunch of stuff ontop of your 9800GX2 before you install into your system, as it might not work afterwards.