Scientific American has an article (Umair Irfan) from Dec. 2014 shedding light on how lithium batteries, when packed together, can sometimes start fires (after one of them has an internal short circuit) even if not plugged into anything.
The NTSB says that new rules are needed concerning the shipments of lithium batteries in bulk, but apparently not regarding use by individual consumers in cell phones and laptops, ABC story
But shipping lithium batteries (which burn as hot as 1100 degrees F) as cargo on passenger planes is simply unsafe, as in this NBC News story. Let unsaid is whether there is an issue with commercial shipment on freight planes (like UPS, FedEx) or in long haul trucking. This is a big deal, as consumers need lithium batteries for everything, and they will probably be key in designing all-electric cars with sufficient range.