In http://www.boeing.com/news/releases/2002/q1/nr_020319g.html, Boeing announces a Technology Demonstrator Airplane, based on a 737-900. I guess Alaska, Continental, Korean, and KLM aren't accepting the 737-900s as fast as Boeing would like? Or is Boeing cramming so much technology into the demonstrator that they need the largest 737 airframe they have? :-)