XBMC on the Apple TV (Generation 2) is a pretty awesome project. I just installed it (jailbreak + installation less than 30 minutes) and now I am watching 720p MKV series on my TV without any hiccups at all! Very impressed by the XBMC team. Now I will probably get rid of my old Mac Mini! Relevant link: http://wiki.xbmc.org/index.php?title=Install_XBMC_on_ATV2