The new route to Gillette may actually be useful to me if I ever need to urgently get to the home of my sister who lives in Newcastle, WY, since Gillette is the nearest airport. Previously, the only service to Gillette was through Denver. I am assuming that it is the energy boom in the two cities that is leading to this service being started.

Unless you have an energy-industry job that is paying for the ticket, I cannot see why anyone would find it necessary to ever fly to Rock Springs from SLC. The two places are not that far apart. But then again, I have a bias against all things Rock Springs, as I pontificate upon in this thread, starting with post #20:
http://www.flyertalk.com/forum/showthread.php?t=798536