I concur most heartily with this! You can call customer service from the plane in most cases, and they have the very same access to the reservations system that the gate agents do.

Before cell phones were available, many times, I'd hang a left to the pay phones and call the airline. On several occasions, I had my alternate reservations confirmed while everyone was queuing up...went a got some chow, got back to the gate area while the line was still about half full.

But also, one is faced with redoing reservations with the hotel and car rental agencies. And it can take some considerable time, too. Make sure you leave with a full charge on the cell phone, and also make sure your recharger is in your carryon in case you need to recharge the phone. There are often plugs available if you look really hard for one. Doesn't help, though, if you are still stuck on the plane, so again, make sure you have a full charge.