Found this plug-in that may allow you to connect to PMS from within XBMC on your ATV 2. I installed it on my iPhone through iFile and once I logged in to my Plex account, I can see my folders. Too bad I'm not at home and my Mac is shut down. Cannot confirm it actually works, but installing an addons from a zip to the ATV looks like a painful process. May try it out when I get back home.