The most recent info is that the Malaysian Prime Minister said that the flight was still pinging satellites at 8:11 am local time - more than 90 minutes after it would have landed at Beijing according to the original schedule.
If this info is really correct, it appears from the map that the authorities know from the satellite ping the distance from the satellite (the radius) but can not tell from the satellite ping where along the arc the aircraft was.
One theory I had was that muzzie terrorists hijacked the plane in order to use it on a suicide attack against the US base at Diego Garcia in the Indian Ocean. Perhaps this was their plan, but it seems foolish because an aircraft is likely to be detected and intercepted before it got close to DG. But then again, they did manage to hit the Pentagon. On this theory, perhaps they ran out of fuel or screwed up and hit the water flying low as they approached DG before they got within radar range to be detected.