I have spent years trying to figure out the transit system, and let me tell you this.. It's complicated.
So here is a post more so for my own convenience.
I find it most helpful to enter "Bus Transit" and desired city and state into http://www.bing.com/.
Then after that try to compare times from local areas and hope for the best..
Someone really needs to put together something that works all these systems together.. But at least they exist. I guess the less than $2 it costs to get from harrisburg to shippensburg is worth it, in the long run.