From tomorrow (Dec 8, 06), it will be legal in the UK to use miniature battery-powered FM transmitters that allow in-car radios to pick up music wirelessly from iPods and other personal music players.
Other such devices work with home hi-fi tuners and radios - and these become legal, too, if they conform to revised regulations.
Both types have been sold clandestinely in the UK for ages - though sales came out into the open after Ofcom heavily hinted in the summer that it was going to relax the regulations.