Myself and three friends flew to Fort Lauderdale and back with our bikes. We broke them down and put them in cardboard picture frame boxes. No trouble at security and no fees. In Fort Lauderdale we put them together out on the sidewalk and then road to South Beach straight from the airport. We left the boxes in the airline's office. Later in Miami we put all the bikes and ourselves in a rented Mitsubishi Eclipse convertible and drove to Key West, then back, stopped at Business Cycles, then got our boxes, broke the bikes down again and came back to Chicago, where we put the bikes back together again on the floor next to the baggage claim at Midway and then rode home.

So I guess the answer is yes, you can take a bike with you on a flight. Sorry for the long post but the original question made me think about that trip and how much fun I had. And while I'm at it I will say that I was very weary of taking my bike apart and jamming it in a cardboard box, but the fun we had riding and everything else was worth it. Sometimes you have to put a nick in your paint in the name of travel and good times and whatnot..