Some interesting things in XBMC changelog recently:
2007-06-30 9486 added: rtsp support in libavformat for dvdplayer, untested as I haven't found any rtsp stream of supported type (mp3, h264, aac), wmv streams from windows media player is not supported at the moment
2007-06-28 9468 added: allow dvdplayer to use ffmpegs built-in stream handlers for rtp/rtsp/sdp/udp streams. it's abit unreliable at the moment on xbox atleast as it might lockup xbmc if there is nothing to stream. (this requires recompiled ffmpeg dll's, with network and protocols enabled).
Haven't looked into it yet but this may be promising for live streaming of TV.
Hope to get some time next week to work on the scripts again been very busy the last 2 weeks