He posted a handy-dandy little chart to help you figure out what's ok, and what's not. If only he could sort out the logic.
Here's what the TSA has to say about batteries:
Lithium-ion batteries, often found in laptop computers, differ from primary lithium batteries, which are often used in cameras. Some newer AA-size batteries are also primary lithium.
While there is no explosion hazard associated with either kind of battery, the Federal Aviation Administration has studied fire hazards associated with both primary and lithium-ion cells, and their extensive research is publicly available. As a result of this research, the FAA no longer allows large, palletized shipments of these batteries to be transported as cargo on passenger aircraft.
The research also shows that an explosion will not result from shorting or damaging either lithium-ion or primary lithium batteries. Both are, however, extremely flammable. Primary lithium batteries cannot be extinguished with firefighting agents normally carried on aircraft, whereas lithium-ion batteries are easily extinguished by most common extinguishing agents, including those carried on board commercial aircraft.
TSA has and will continue to work closely with the FAA on potential aviation safety and security issues, and TSA security officers are thoroughly and continually trained to find explosive threats. TSA does not have plans to change security regulations for electronic devices powered by lithium batteries.
I'm not really certain what they're saying there - something about non-explosive lithium batteries having something to do with TSA explosive threats. Not that we really need to understand anything except...
The terrorists are coming! The terrorists are coming!