Is there a wireless product that would plug a camera mounted transmitter into the headphone jack of my camcorder, and then use a receiver on my belt, that I'd plug my Sony phones into?

I good use for such a product would be audio monitoring while using a steadicam, or letting a boompole operator move about more freely.

Thanks...

I can think of a couple solutions off the top of my head:

1) Use a wireless hearing-assistance device. Most transmitters are meant to be plugged into a wall outlet, but some are meant for a tour guide to talk to tourists that wear the receivers. Try http://www.williamssound.com/Products/TGS100.html

2) If you're on a tight budget, you can find a $20 FM transmitter (sold at Target and Radio Shack) and a cheap walkman for a receiver.

Also, Shure makes some wireless in-ear monitoring systems, which might work for you.

There are usually cheap FM wireless tie clip mikes on Ebay. Though you can plug any small mic jac into the transmitter. Ie from a mic or even the headphone out on your camera. You can get a green and a red, on different bands. My friend has a pair that work really well. I have a pair, one works really well. The other poorly. They are ok i guess, fine for monitoring, or communicating between each other using a cheap walkman, or mini disk as a device for recieving. They are mono though, and the attached battery pack has a belt clip, i suppose it would have to be taped up somewhere if you were monitoring a sound man or camera on a crane or something. You could use them as a mic wired to the camera too, although youd be better making a wire up so you can wear the reciever unit on a belt, as to let the antena, which is a wire, hand loose. They are good for static work, but i would be uncomfortable with them on the move, as you may pick up a local radio station and spoil your audio!
Someone i know bought some 'gemini' UHF radio mics. The quality was fantastic, no inteference at all. But they were expensive (£189 each), and required mains supply for a reciever) Again its worth baring in mind that usually if you but a radio mic set up, the actual microphone itself can be changed or replaced. If you have a small transmitter unit with a wired mic attached it means you can get directional audio from the oposite side of the room to where your camera may be by leaving a mic over there.