The latest air-safety threat
Now the TSA is afraid that spare lithium batteries will spontaneously combust. Or that somebody will try to light them instead of their shoe, but if so why are thay banned from checked baggage and not from carry-ons?
Never mind that they're just as likely to combust inside a laptop. Maybe more, since an external short might develop. (Added 08:55 sbisson points out that there's a real reason for the apparent anomaly: cabin fire extinguishers can cope with lithium fires, while the automatic ones in the baggage hold can't. But you can still check a laptop through, and those have been known to burst into flames.)
(From BoingBoing.) Note that most batteries installed in devices are permitted, and even a lot of add-on batteries. Forget about checking through a big pile of camcorder batteries, though.