Can't comment on mapping tile-based solutions for integration into an application.
But here is a solution that has other developers integrating into their Route and Plan managed applications:
http://www.mobiumgps.com/contactus.html
Called MOBIUM, this provides a nice hands-free turn-by-turn method of following a route.
They also allow for caching a route tile-list locally on a device so that only the route needs mapping content loaded on the device.
-sean
