Some bright sparks have come up with a way of adding a plex client to an non jail broken Apple TVs.
It uses a DNS hack on the movie trailers - which may require the ATV to think it's on a US account.
You put some some software on a machine with python and pint the apple tv's DNS to that machine. The machine intercepts a call to trailers.apple.com and forwards it off you your autodetected plex server.
Then it plays the video.
Most impressive.
http://elan.plexapp.com/2013/06/04/introducing-plexconnect-an-appletv-client-which-thinks-different/