From SpaceX, regarding the September 29 launch of an upgraded Falcon 9 from Vandenberg AFB in California:
Though not a primary mission objective, SpaceX was also able to initiate two engine relights on the first stage. For the first restart burn, we lit three engines to do a supersonic retro propulsion, which we believe may be the first attempt by any rocket stage. The first restart burn was completed well and enabled the stage to survive reentering the atmosphere in a controlled fashion.
SpaceX then lit the center engine for a single engine burn. That relight also went well, however we exceeded the roll control authority of the attitude control thrusters. This particular stage was not equipped with landing gear which could have helped stabilize the stage like fins would on an aircraft. The stage ended up spinning to a degree that was greater than we could control with the gas thrusters on board and ultimately we hit the water relatively hard.
However, SpaceX recovered portions of the stage and now, along with the Grasshopper tests, we believe we have all the pieces to achieve a full recovery of the boost stage.
Other pictures and descriptions from the launch are available at SpaceX, Upgraded Falcon 9 Mission Overview.
Video from the launch (the first stage relight from the perspective of a camera on the first stage appears at about the 2:40 mark in the video):