Dennis Bushnell [http://www.SandSmachine.com/bp_bushn.htm] fabricated most of the original Counterpoints and still builds them for companies in the UK as well as AngleTech's Harmony. Bilenky builds the ViewPoint in-house at their shop near Philadephia, PA.
Howdy from Tucson!
Asides of what Mark mentioned there is also a German tandem, called the Pino by Hase Spezialrader that is similar and there are several dealers in the US. They do both steel and titanium (31 lbs and just under $9,000) and are also a very hi-quality machine.
Rudy & Kay/Zona tandem