I'm not going to go picking through Google, but there is absolutely zero question that cell phones work just fine on commercial airliners. (Well, "fine" may be too strong a term; read on for why. But they work, they're just more prone to dropouts.) The average cell phone tower covers an area of about 3-5 miles or so, maybe more or less depending on surrounding terrain. But what most people don't understand is that the 3-5 mile range isn't merely along the ground; it also works just as far straight up in the air. (And, indeed, the signals can often go farther, since there's not much terrain up there.) So unless your flight is cruising at a very high altitude (25,000 to 30,000 feet and up), your phone will work just as it does on the ground. (And as I just noted, it'll probably work even at 30,000 feet and up ... the signals will just tend to get steadily worse in quality the higher you go.) All the 9/11 flights spent much of their time in the air at far lower altitudes, so the people on board wouldn't have had any trouble at all making calls.
There are two reasons for the urban legend that cell phones can't work on airplanes (and its wackier cousin, the urban legend that merely turning a cell phone on during flight will cause the electronic controls of the plane to start spitting out false data in the cockpit and risk putting the flight into a death spiral). Both are almost entirely based on the desire of both the airline and cell phone industries not to have people make calls on planes:
1) [The following is somewhat oversimplified, but going into dull technical details will add nothing meaningful to the explanation.] Cell phones work by handing off your phone call from one cell phone tower to another as you move around (usually by driving). Usually, you'll only be putting out a strong signal to one tower at any given point on the ground, and it takes your call. As you drive and one tower notices your signal getting weaker, it'll pass your call off to the next tower down the line. In a congested area, your call may be intercepted by several towers at once, but the system is smart enough to sort it out and say, "Okay, tower X, you take it." However, it does take some computing power to hand those calls off, and the system isn't perfect, thus sometimes your phone will just go dead when the handoff is attempted. (It will, of course, also go dead if the only tower in the area you just drove into is full, but that scenario's not relevant here.) Now, imagine yourself 3 or 4 miles up in the sky, flipping on your cell phone. The moment you try to place a call, it's going to bounce off dozens of towers on the ground, because your line of sight from the plane covers such a gigantic area of the ground. It would add major congestion your cell phone provider's system, particularly if there were thousands of people doing it from the sky at every moment. In addition, the chances of your call getting dropped would be much higher than it is when you're on the ground. Again, multiply that by thousands of people making such calls at any given moment. You'd end up with lots of angry cell phone users that think their cell phone service stinks. Obviously, the cell phone companies aren't too thrilled about either of these scenarios, so they're content to have you keep your phone off while you're in the air.
2) The airlines just don't want the multiple hassles. First of all, they know the urban legend is out there about "cell phones making airline electronics go haywire." They don't want passengers freaking out the moment someone pulls a cell phone out of their pocket and flips it on.
Second, they don't want their already angry customers, who have already gone through the hell that is the boarding process and are now enduring a much lower level of service on board than they used to get, to also have to put up with having half the people on the plane making loud obnoxious cell phone calls throughout the flight. It's just one more thing to really get on the nerves of people that are already pissed off and miserable just being on the plane in the first place.
Third, because of the urban legend, they know that if anything were to happen on board that caused the slightest injury to someone - say, bad turbulence - and the injured person saw another passenger using a cell phone around the same time, there's a very good chance that passenger will sue, claiming "the cell phone did it." (It's total junk science, but that's never stopped gigantic monetary payouts before.)
Fourth, if you must make a call at all, a lot of airlines want you to use the Verizon AirFone that's built into the back of all their seats ... you know, the one that costs $4 just to connect and then $4 a minute after that. They know you're not going to do that in a million years if you've got 1000 free anytime minutes on your own cell phone.
So, just like with the cell phone companies, all in all the airlines are quite happy to have you keep your phone in your purse and your mouth closed while in the air.
Regular cell phone usage in the air is, however, probably going to start becoming a reality at some point in the next few years, as cell phone technology gets even better than it already is (more towers, fewer dropouts, better switching equipment, etc ... less reason for the cell phone companies to worry about overstressed systems) and as the government finally gets around to proving empirically that using a cell phone on board a modern aircraft does not cause the instruments in the cockpit to go nuts. (And they did indeed announce just a couple of weeks ago that they are going to start scientific testing of the effects of cell phones on airplane electronics, to settle the issue once and for all.) It'll still annoy the hell out of the other passengers, but once the airlines no longer have a convenient excuse to disallow it, a lot of people will do it.
For now though, if you still don't believe the phones will work, just sneak your phone open while you're in the air and try to call home and listen to your own answering machine message ... or even just send a text message to someone and have them message you back. It'll work.
Four airliners were flown by remote control? It's not even possible.
Well ... it's possible. It most certainly did not happen on 9/11, but the most modern Airbuses pretty much fly themselves, to the extent that a lot of pilots don't like them because they don't have enough control over what's going on. You could certainly rig up a Boeing to fly by remote control, but the number of people involved to pull it off on four commercial Boeings full of live passengers would cause even the most credulous conspiracy theorist to think twice about even considering the possibility.
Oh, okay, who am I kidding. They'll believe anything.