This type of fire has been reported on numerous laptop computers in the last five years. It is not a pretty sight, and in laptops, some people have had their laps burned by the thermal runaway.

Here's a very recent incident of a Dell laptop going up in flames:

http://consumerist.com/consumer/battery/another-dell-laptop-ablaze-190546.php

The problem isn't just in Dell laptops -- I've seen reports of the same problem on HP, Apple and Fujistu.

Also, the problem isn't restricted to only NiCd batteries. I'm seeing increasing reports of fires and heating problems on Lithium-Ion battery packs. The NTSB is investigating whether the fire on FedEx flight 1307 (A DC-8, fire on the ground) was caused by laptop batteries that were Lithium-Ion.