Its very frustrating that nothing has happened so far with any of the broadcasters.
I know there are problems with certain broadcasters, in particular the BBC, because of their "public service remit". The BBC for example would be breaking the rules of their charter if they were to start selling shows under the banner of BBC TV. The rights of the shows would have to transfered to BBC Worldwide (which allows profit through means of selling, and usually has control of BBC shows sold on DVD). Hence they wouldn't be in a position to start selling a show like Eastenders, or Doctor Who 24 hours after broadcast like happens in the US.
Channel 4 have started selling shows such as Lost after broadcast, but its not iPod compatible at the mo. I think whats happened is that companies have seen the potential in selling shows via the Web, and are attempting their own routes, before they agree to sell the shows via iTunes.
There is hope, remember Europe didn't get an online Music Store via iTunes for ages after the US got theirs! Perhaps it'll be the same with the video content?