As of yesterday, there are restrictions on loose lithium batteries that are packed in checked luggage. Because of the extremely flammable nature of these batteries and the the fact that primary lithium batteries cannot be extinguished with firefighting agents normally carried on aircraft, these restrictions were put in place by the FAA.
While I’m sure not many of us photographers would pack our camera gear in the checked luggage (at least not if we want to see it or see it working on the other side), this could impact you if you just want to lighten your carry-on. It appears that if you just keep the protective cover on your camera batteries there shouldn’t be a problem. (Personally, I wouldn’t risk it either way).
Side Blur: I find it funny that on the TSA website, they talk about Lithium-Ion batteries that are commonly found in laptop computers right next to a photo of a camera Lithium-Ion battery.
Thanks to Andy Chu for first pointing out this restriction…