MapQuest 2.0

I was reading over O'Reilly's 'What is Web 2.0' article, and I came across this line:

Imagine if MapQuest had done the same thing, harnessing their users to annotate maps and directions, adding layers
of value. It would have been much more difficult for competitors to enter the market just by licensing the base data.

Cool idea, right? But where do you start?

One way would be to allow users to adjust estimated travel time. If
MapQuest comes back with 45 minutes, and you know you always do it in 30, type in your estimate, press submit, and it goes into the
database. When enough get compiled, the user's average response is
displayed alongside the algorithmic one.

Another way would be to allow user submitted pictures of difficult
intersections, or landmarks to watch out for. Maybe even things to
check out nearby?

As far as implementation, itd be nice if you could get this service
to ride on somebody else who has already paid for the data. Query
MapQuest for the directions, and retrieve the annotations alongside it.