Colorado Railcar has definitely NOT given up on the DMU.
They have recently completed several more new bilevel DMUs for South Florida Regional Transit (the Tri-Rail operation between West Palm Beach and Miami) and have begun working on an order of five single-level Aero DMUs and trailers for TriMet in Portland, Ore. These will operate on the regional rail line between the Portland suburbs of Beaverton and Wilsonville, which is scheduled to open in September 2008.
There is also a possibility of them building several Aeros for the State of Vermont, which would operate them in "Vermonter" service between St. Albans, Vt. and New Haven, Conn., replacing the current P42/Amfleet consists used in the service.