Although you can get some thingy which transmits something or other to your iPod... I believe whatever it is is illegal in the UK?
It transmits *from* the iPod, to a car stereo - thereby making it wire-free. It's illegal in the UK due to archaic radio broadcast licensing laws, even though it has a very small broadcasting radius. There are a few different brands, but they all do the same thing.
AppleMacster