Agree with phlux here, its the 'terms of service' that, if they care, they will come after you with. That being said, did you approach them with an offer to sell them the app?

In the Bay Area we have a variety of 'CalTrain' apps which vary in quality and utility, they all rely on the same data. None (in my opinon) capture the elegant simplicity of the original PalmOS application.

In terms of infrastructure improvement, a generalized mash-up of all public transit combined with location based sensing and destination intent would seem to be the end goal. Maybe with an overflow timeout that links to Uber :-)