TSA prohibited items
The US Transportation Security Administration has updated its Prohibited Items list. If you're traveling by air in the US anytime soon, take a look at the list. Also check it again before you leave; it may be updated frequently.
Note that, in the US, gels and liquids can be packed in checked baggage, just not in carry-on bags.
Also note that, in the US, electronic devices are not prohibited in carry-on bags. I traveled this weekend with my full usual complement of electronics (MacBook, Treo, iPod, digital camera) and had no problem taking them on the plane with me.