Noted in a comment at a much earlier related FreeRepublic thread, the transponders on these planes were recently disabled and many of these planes are serviced in Malaysia:
"last year, Boeing directed operators of its various jets to replace Honeywell Emergency Locator Transponders on their aircraft. The models involved included the 777-200. A Honeywell transponder on a 787 owned by Ethiopian Airlines caught fire on the ground in London and heavily damaged the aircraft."One supporting article: UK AAIB: Boeing 787 emergency locator transmitters should be disabled Also posted earlier on another thread via WSJ link:
Malaysia Airlines Says Plane Had No History of MalfunctionLast Safety Inspection 10 Days Ago, Which Was Earlier Than required, It Says
Malaysia Airlines said its missing plane had its last safety inspection 10 days ago--earlier than required --and didn't have a history of malfunction. WSJ streaming updates
"...what is shocking also, imo, is the number of planes flying for domestic US airlines that have their maintenance performed in malaysia. http://mae.malaysiaairlines.co...
Looks like it was not the plane they found.