Is it possible? Can we play NTSC movies on pal boxes (and vice versa) smoothly without any jerky hickups..?

Maybe its too early to say, but with xbmc's latest option called 'Adjust framerate' or 'dynamic framerate conversions' things surely look promising.

Previously watching NTSC encoded movies with 23.976 FPS on my PAL box resulted in jerky playback. With the new option enabled its perfectly smooth. Same for playing PAL encoded movies (25fps) on an NTSC box.

Be sure to try it out and let us know what your experience with this exciting new option is! See the forum here: http://xboxmediaplayer.de for more info.