yup! I was doing a show in cleveland Mississippi afew yrs back,and broke a string in the middle of a song,My lead was coming so another guitar player handed me his guitar and I handed him mine at the same time we both grabed each insturment and got the beans knocked outta us!!!
Wireless was invented by our bassist, who fell off the stage during a concert in the early 70's. Okay, so it didn't make any sound at the time (he did, though), but the concept was there.
BTW, speaking of pickups. I once saw a really cool Fender strat in a shop, where the middle pickup had been mounted on two steel bars and a lever could be used to move it freely between the two outer pickups, which were adjusted down a bit so the movable mid-pickup controlled the sound better.
The cool thing was that this could be done while playing, so one could shift the sound seamlessly for example in the middle of a chord or a long note. It was a professional job done to it and it was way too expensive for me to buy at the time, but I have been thinking of doing something similar myself, some day..