Malaysia Airlines Flight 370 disappeared over the South China Sea on the 8th of March, and recently presumed to of crashed about 1500 miles southwest of Perth, Australia with all 239 passengers and crew presumed dead. The aircraft, a Boeing 777-2H6ER (the H6 being Malaysia Airlines' customer code with Boeing) with the registration 9M-MRO was delivered new to Malaysia Airlines, and had one ground incident where its wingtip struck the tail of a China Eastern Airlines Airbus A340 and broke off, it was subsequently repaired and placed back into service. It was operating a codeshare with China Southern Airlines as Flight 748. If the wreckage isn't found, and no survivors located, then it would be the worst accident ever to befall a Malaysia Airlines aircraft and the Boeing 777 in general.
UPDATE: Satellite images from Thailand show nearly 300 objects in the search area of where Malaysia Airlines Flight 370 has thought to have crashed, although unknown if these are from the airliner or not, Australian officials have said that this is the most credible lead we have yet.
UPDATE: Chinese ships towing an American 'Black Box' locator have discovered pings at about 37.5Khz, about the same frequency as those used on the Black Boxes on an aircraft, it is unknown if these belong to MH370, but they picked two signals up, one being less than 1.5 miles from the other, although an exact location hasn't been disclosed.
UPDATE: The Australians and Chinese have picked up the signals believed to be from the Cockpit Voice Recorder and Flight Data Recorder from the missing flight MH370, the search has switched from the surface of the Southern Indian Ocean to the underwater depths of that area in looking for anything that could belong to the missing flight.