Thanks for that link. Would be interesting to know whether this battery fire/explosion occurred under load, or under recharge.
This is key to understanding it.
From my reading of the report that greblaw posted, apart from mechanical or thermal damage the most likely risks of thermal runaway are due to either overcharging or attempting to charge a 'dead flat' battery. My understanding of Li-ion battery caused fires, is that they have started under the latter circumstances where aircraft with discharged batteries have been standing idle for some time with the batteries off-line and a GPU has then been applied to the 'flat' battery.
I can't see an 'almost new' 787 having any of its batteries in a discharged state even if it has been stood in a hangar for a few days. This has to be something else.
Guess we'll need to wait and see.