The following link is a recording of a cockpit announcement on a JetBlue flight from San Juan to JFK.
http://www.nypost.com/video?vxSiteId...&vxBitrate=700
In announcing that nothing is allowed on your laps the Captain includes "reading materials."
With respect to flights entirely within the "lower 48," rules like this may make some people think long and hard about boarding any flight expected to last longer than 2 hours.