I use my iPhone camera and video camera quite a bit, but if a newly discovered Apple patent is any indication, you may not be doing it at some venues for long.
The software on the iPhone would apparently work with sensors installed at the venue. The sensors would theoretically be turned on when a show or sporting event starts, which would activate the software. Everything on the iPhone would work normally, except the camera.
Mashable brings up an interesting point — could the venue or Apple charge consumers a fee to unlock the camera at an event? Seems like a way for someone to make money.