Is an antenna an antenna or are there different kinds?
 

My laptop has a built-in antenna that extends about 2 feet, which I believe might be for cellular phone communication, but maybe it is used like a walkie talkie. How can I determine what type of antenna this is (I've actually opened the rubber case and looked at it)? Is it possible that this could be used with a 802.11 chip, rather than having a tightly rapped coil bunched up inside my laptop?

antennas (especially for transmitting radio frequencies) are designed to specific lengths (tuned) so they resonate best on the frequency the transmitter is using, i suggest you find the owners manual for that laptop and find out what exactly it is used for...

the wrong antenna on a radio transmitter can cause high SWR and possibly burn up the transmitting drivers & finals (transistors)...