This doesn't really sound like Apple news, but bear with me.
Today, the coroner said the cause of the fire was an overheated laptop, left on a couch.
The coroner refused to release the make and model of the laptop, but CBC quite gleefully has added a picture of an Apple Powerbook, mentioning that this is "one of several computers" that has had problems with overheating batteries.
So, let the speculation begin, but don't expect any answers. Still, I'm glad that I keep my Macbook safely (sic) on a desk with good ventilation....