Lockheed Martin has been hard at work getting the Orion space capsule ready for its first unmanned launch, scheduled for sometime in 2014. The first manned launch was supposed to happen two years later, but it's now been pushed back, dragging manned deep-space exploration along with it.
Instead of 2016, we're now looking at 2021 for the first launch of a manned Orion capsule, and this is assuming that the 2014 test mission (including launch, a few high orbits, and a high-energy reentry) is a success. It's a big disappointment, since in many ways, Orion is a look backward in spacecraft design, while the now-retired space shuttle was a look forward towards those space planes we've all been fantasizing about. The hope was that Orion would make access to space faster, cheaper, and more reliable, but so far, it doesn't seem to be shaping up that way.
From the sound of things, the problem here might not be the capsule itself, but rather the combination of the capsule and rocket that it'll get to space on top of. The new 2021 launch date fits in with the testing schedule for the Space Launch System, which should have its first flight in 2017 and first crewed flight in 2021, hypothetically followed by a trip to an asteroid in 2025 and a journey to Mars around 2030. Since the SLS won't be ready by 2014, Lockheed Martin currently plans to launch the first Orion on one of their own Delta IV cargo rockets, which could meet NASA's criteria for launching humans as well.