Thank you for the link - I definitely found it interesting.
I am aware that PLANESCAPE was discontinued as campaign set per se, but as I have said above, ALL of the elements that made up the Setting - Sigil, the inner and outer planes etc, ALL exist in 4th editiion D+D, okay so you might have to take the PLANESCAPE title away and call it something different (call it OUTLANDS or Dungeons and Dragons Multiverse, or Sigil and Beyond. etc) Call it Sigil Days if you must!!!! But the planes themselves are stil a valid setting for 4th edition adventure. And if it proved popular enough it might be enough for WOTC to bring the PLANESCAPE setting back.