i act as a bit of a paranoid nutter and actually shut off my laptop when flying international. it's pretty much the only time i do that. the question is not answered to my satisfaction, so that's the choice i make in response.
That said, this was years ago. I have heard that they do try to clone the drive now.
Plausible deniability and FDE (for the partition you care about at least).
I didn't like it though.