Another thought on SATCOM derived lines of position:
Depending on how long the backlogs of inmarsat are, it should be possible to find data of previous flights of the a/c in the logs. Whatever data is logged there (signal strength, round trip delay, dopplershift, ???), it should be possible to calibrate specifics of MH370 transceiver against data from previous flights. For those flights the exact position, height and speed vector should be known for the points in time when the pings where exchanged.
Probably a bunch of RF engineers is doing extra shifts right now. Im pretty confident, in the end it will boil down to the question, where did MH370 go to after 8:11 MYT.