Whilst we wait for proper rtmp support in some fashion in curl or some other source, I propose a solution. Open the iPlayer page (with flash plugin) in Safari, and turn the remote into a mouse controller.
I have the mouse controller done (ish, it's clunky to use, but works)
I have NitoTV with webkit installed, so I will put Safari on, and probably have a perl script to open safari at iPlayer.
I'll report back if I get it working (for any interested UK people)
I'm sure I've never installed WebKit on my AppleTV but it seems to be there. I've certainly been able to write a basic frappliance that will load a web page containing the RealPlayer or Flash plugin.
It is possible with a little jiggery pokery to show a webkit view in a frappliance by getting a reference to the shielding window that is used in full screen mode and setting a window to that height. I don't think I found the optimum settings but there were issues of flickering which I solved at least partially by setting the view scale to 1.1.
However the biggest problem is that, as I understand it, the licence agreement for the Flash plugin specifically prohibits its installation on set-top boxes and games consoles and the like. A frappliance for Front Row on the Mac should be OK but use on the AppleTV is likely to be a breach of the EULA.