I just came across a poll conducted by Go Group, LLC. 307 frequent fliers were asked to pick the one travel accessory they can't leave behind. Of the 5 choices, paper book/magazine lead by a considerable margin (188 votes). Second and third place was taken by laptop (27 votes) and neck pillow (24 votes). Ebook readers came in fourth place with only 7 votes.
I really thought it would be higher than that. I was expecting more of the book voters to have switched over by now.