NASA Engineering and Safety Center's (NESC) Max Launch Abort System (MLAS) has been in development since mid-2007 and had originally planned a flight test in September 2008. The agency has told Hyperbola that its launch is scheduled for no earlier than 27 March this year
The US space agency describes MLAS as
a less-well-developed concept that does have the potential to help Constellation. [The 27 March launch] will be the first demonstration in a passively stabilized LAS on a vehicle in this size and weight class. We will get aeroacoustic data from the faired capsule in flight that will give us a better idea if there are potentially harmful noise levels. In addition, data from the parachute element will help validate simulation tools and techniques for Orion's parachute system development.