Update - Vietnam SAR
Sun has set and soon we should get reports from airborne search. The most recent I've seen, from a Thanh Nien reporter aboard Mi-171 helicopter no 02, was negative however. It took off after the AN-26s had returned to investigate at N072740 E1025848. This is in the vicinity of the oils slick spotted yesterday but further west.
However, flying at 500 metres (1500 ft) or lower, the crew judged the slick not to be oil.
The crew also observed several objects floating in the sea, which on closer observation were determined not to be from MH370.
I guess we will have some more of these false alarms, until the shipborne search starts in earnest as vessels arrive in the area. So far I have not seen any report of ships in action which would be capable of locating the CVR and FDR pinger.