TriMet, The Open Planning Project, and developers of FivePoints, OneBusAway, Graphserver, and byCycle are working on an ambitious open-source multi-modal trip planner (the project name is OpenTripPlanner).
When finished, the multi-modal trip planner software will plan journeys by a combination of biking, walking, and transit in the areas where it has been implemented. For regions that wish to implement the trip planner, they will need to use in-house resources or hire a firm to install, host, and manage the software. Information on transit service, walking routes, and biking routes in the necessary formats will be one of the most important prerequisites for implementing the open-source multi-modal trip planner.
Check out the OpenTripPlanner site or join the developer discussion list to learn more and follow along with the effort.