+1 on the previous post.

I left a very nice Lenovo Ultrabook on a flight last year. I eventually got my Amex business travel insurance to pay the max of $250 which I sent to my company to offset the rather large cost of replacing it.

Now I'm very sensitive to making sure everything goes with me when I deplane. I either put it up in my bag before we land. If I don't, I make a point of taking it out of the seat back before I get up. I lay it in the seat so I will notice that its still there or at least someone around me will remind that I left something. My company's policy requires me to encrypt the hard disk to protect the data, which is worth way more than the hardware.