Starting tomorrow, passengers flying into the U.S. will face tougher security that may include short interviews at either check in or the gate. (American Airlines has been doing this for a few months already.) The airlines are now saying passengers should arrive even earlier than previously suggested so all security can be completed and the planes can leave on time.
If you are flying domestically, all electronics larger than a cellphone--including mini tablets, ereaders, handheld games--will have to be removed at security. (Not sure if this affects Precheck.)
The TSA says this is all to not prevent laptops from flying. (The TSA does't want to ban them in carry on bags if they don't have to and the FAA doesn't want them in checked luggage because of the fire risk.)