If the coolant in the radiator isn't even warm, then it isn't circulating, which is why your engine is overheating. Suspect the thermostat. Remove it. Boil it in water. If it doesn't start to open at its stamped temperature, then it is faulty. They are inexpensive to replace. A candy or meat thermometer can be used, but the thermostat should certainly open once the water starts boiling. It should actually start to open a bit before the water starts boiling (145, 160, 180, or 190 degrees are typical ratings).
If you were waiting in line and you overheated my first guess would be a dead radiator fan. Or maybe a relay to the fan....but probably something to do with the fan. Do this: idle in your driveway and watch the temp display on the dash. When it hits the regular running temperature, or just starts to go over you should hear the distinct sound of a fan kicking on. This won't be some wimpy fan either, you'll definitely hear it. If you don't hear it, and the temp keeps going up...you have a fan issue.
Also, if your car hit 260 degrees you may very well have cooked a few of your gaskets. That can lead to very serious issues involving massive engine overhaul. If you aren't car-savy than you should really take it to get checked out somewhere.
Your thermostate will open at 195. This is the tempature that has been used for the most part sense the mid to late 1970's. That is because of the manufactures makeing the cars more envriomentally friendly with the polution control systems.
Follow the above advise, it could be the thermostat, hose, or fan issue. And yes you may have caused engine damage by letting the engine go past 260, so be sure to have it throughly check out.
If you ever have an issue like that please turn off the AC, roll down the windows and turn the heat to max and the fan to high speed. This will make you as the passanger hot in the summer but could very well get your car to the mechanic and keep from destroying your engine. The heater core will act like a minature radiator and help to remove the excess heat from the engine.