Tom Robinson wrote:

an iTrip device or similar which allows you to broadcast on FM,

An iTrip is plausible. It just could be possible it was not a
deliberate hack but the perpetrators discovered it accidentally.

I thought (with my telecoms engineer hat on) iTrips were not yet legal
in the UK and are still subject to Ofcom consultation not complete
until end of 2006.

Having said that, they are on sale in UK, and (not sure) I think I read
somewhere they carry CE marks which sort of makes them European legal
(cue pedantic discussion UK v. EU law).

--
Nick