Any more information on playing back 1080P? Specially anyone managed to playback 1080P mkv's successfully?

Main reason I want 1080P is because of hassle of converting, that even if converting can actually recognize 1080P mkv and subtitles properly. Not mention it takes a while to convert 30 mins long 1080P files. Last time it took 20-30 minutes for conversion for N800 and then it still didn't play! N800 doesn't like high bitrate 800x480 video, hopefully N900 is better than this!