[dsl]

This is called dead reckoning[1]. Given the previous two locations you can tell the speed. Since you know the route the bus will take, you just plot it where it would be if it never stopped moving since the last update. It's pretty close 90% of the time.

1. http://en.wikipedia.org/wiki/Dead_reckoning

[w-ll]

I'm not sure if the're using dead reckoning. I just saw one turn. To me this looks more like gps.

Also, Go Wolf Pack!

[dsl]

As I said, if it is something like a bus where the route is known, dead reckoning is still effective.

Even with GPS you usually only get location updates every few seconds, DR fills in the "smoothness" between updates.