I saw this jet on the flight line at Renton a while back.  It is a 737-10 and is the first one to be in the colors of United Airlines.  It will probably be their first jet in service (assuming the 737-10 ever gets certificated) but, in truth, the development jets are also going to United (again assuming that ever happens) so they are really United’s first jets.  However, you get the gist of what I am saying.