Just wanted to give my experience when standing by for Jetblue this past weekend. The flight was booked solid, but I was relying on the fact that they don't oversell to improve my chances.

On Jetblue you are supposed to call to get on the standby list. You can do it at least one day in advance, possibly earlier. I'm not sure exactly what that list does, since Jetblue still relies on the order of arrival at check-in to determine standby order.

I called reservations and confirmed that the flight was sold out. She told me that they still do not do not oversell flights (I don't know why, since it would seem to be an advantage to oversell by a few seats). I asked if they regularly have no shows, and she told me that they often have a few, but less than most airlines (the fewer number of connecting flights probably causes this). The flight I wanted was very early in the morning, so I assumed there would be a few who overslept.

One difference with standby on Jetblue is that if you have the first flight of the day, but only the first flight, you are allowed to standby for the last flight of the night before. That could really come in handy, but it only applies to the first flight and last flight.

Turns out, about 5 no-shows, and I made it on just fine. I never even said anything to the gate agent, she just had me on the list and called my name and one other standby. Someone grabbed my bag when I got on and they took it to the closest overhead bin to my seat with space. Pretty smooth process overall

PS. The TrueBlue points credited double, meaning the online booking bonus still works if you stand by for a different flight.