Flaming Heck!
The main culprits are Lithium Ion (Li-Ion) batteries and the danger's been openly discussed for a while now.
Some "lucky" users have been quick enough to capture the action - or the aftermath. Click the pics to visit the sites and witness more destruction.

A Dell barbeque at a Japanese conference.

Another day, another Dell.

This is what they mean by "overheating".

Results of the "venting with flame" syndrome.

Another PowerBook meltdown.
There have even been some incidents on aircraft - none too nasty... yet.

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