I have not heard this on any of my recent UA or UX flights. In fact, in almost all cases my seatmate clipped a blackberry to the seat pocket, and I routinely place a book and the case for my QC2's in the seatback pocket to keep them handy. Have never, ever had an issue.

Could indeed be a new mandate from the FAA and a clarification of the rules, but as the rules don't exempt in-flight magazines or the SkyMall catalogues that I can tell, I don't see how they (the FAA or the FAs) can differentiate between those items and similar things (a book, magazine, iPod, etc.), other than the claim that some are passenger "baggage" and the others are not.--and choosing to enforce that seems nonsensical to me.