Yeah, I read the website advertising this years one a couple of months back - at first I thought it was a wind up but there were pics posted from one they did previously.
Apparantly peeps turn up with suitcases that can be opened up to provide various party props. i.e suitcase opening up with optics inside to use as a bar, another with lights, decorations etc, one with the sound, one with a buffet - stuff like that
Quite a cool thing about the organising of whole thing was that they even produced a map/ timetable thing so that if you needed to get off the train where the party was on to go to the toilet (obviously didn't have a suitcase that opened up into one!) then you could work out the best connections to get you back to the party in minimal time...
This is the first I've heard of since reading the site so I guess they must have pulled it off.
Strange and it would be annoying but kinda cool too 8)