This is the first time I've seen a site like this. I've been pondering a system like this for years during long commutes but didn't realize it had a name or following.
The question I have is how do you prevent these vehicles from blocking main lines when you have 50 to 100 (or more) people requesting their individule cars at one time/station? I presume that you would load people on a side spur then wisk them away to the main track(s) but when many people want to leave from the same terminal at the same time (such as with current mass transit) it seems to me that there would be a stack up on any given spur and then a major bottle neck to the whole system since this same scenerio would be occuring up and down the line. (I've enjoyed this discussion and would encourage nay-sayers to put their energy to solving problems rather than tearing down other's ideas!)