Talk about "iPad3" for March 2012 are still on going. Supposedly suppliers still have issues with development of a high def Retina display for the actual "iPad 3" slated for possibly 3rd quater of 2012.
March iPad will most likely be an upgraded iPad 2, just like the iPhone 4S was to the iPhone 4. So mostly a software upgrade including Siri, and a major facelift 6 months (or possibly) later including "hopefully" a Retina display and better battery life.