I think you'll be happy to hear that not only has this idea been worked on starting much earlier than 2008, but I was part of a group to implement this for a city in the US. Service is scheduled to start later this year.
As it turns out - many of the hurdles are non-technical, especially without many examples of pre-existing systems to base it off of.
As it turns out - many of the hurdles are non-technical, especially without many examples of pre-existing systems to base it off of.