The Air Force Research Laboratory (AFRL) and DARPA are working on the X-37B Orbital Test Vehicle, intended to carry new equipment, experiments, components, and satellites into orbit for testing, then return then to Earth. The X-37B may be thought of as a quarter-scale version of the space shuttle, minus the astronauts. The Air Force's Rapid Capabilities Office is responsible for the program to acquire, test, and demonstrate the OTV. A first launch in 2008 is hoped for.
COMMENT: Building a reusable demonstrator of this type makes a lot of sense: not just to have the capability to test and retest equipment in space, but to see if the OTV itself is a workable concept. If it suceeds (or even if it fails in flight) it will contribute a great deal to the design and construction of future reusable spacecraft. However, similar programs have been started by the military and/or NASA many times since the 1950s and have never been funded to completion. So I wish them the best of luck. The environment of space may be harsh, but it's nothing compared to the ones encountered at the Office of Management and Budget and on Capitol Hill.