I almost missed yet another change in the security theater of airline travel in the US. Starting on January 1, 2008, there are restrictions on how you can travel with lithium batteries -- the kind of rechargable batteries you probably have in your laptop, cellphone, MP3 player, digital camera, and so on.
As I read it, for the most part, you can carry your lithium batteries in your devices the way you do today, in your carry-ons or in checked luggage. However, you may not check spare batteries; you must hand-carry spare batteries. There are also new limits on how much lithium you can carry aboard, for most people, this won't be an issue. The TSA also has suggestions on how to pack your batteries in your carry ons to minimize the threat of short-circuiting the battery and starting a fire. You should read the details and figure out your own interpretation. (For grins, here's the FAA analysis of lithium-ion battery fires in aircraft.)
For me, this will mean no longer checking my camera bag or at least the extra batteries. I usually hand-carry my laptop and its spare battery so no issue there. Stil, one more thing to think about.