Using your cell phone during works has always been forbidden. They've increased the penalty* for this and extended it to anything that any supervisor decides looks like a cell phone (wireless headphones**, for example, because they could possibly be mistaken for a bluetooth headset), and for using your cell phone for non-phone uses (such as using it as a music player**). The stupid part of this is that the only (legally) justifiable reasons for having a cell-phone are safety concerns or to keep up production. The only safety hazards are the forklift, which goes nowhere near the desks, and broken equipment that the company is too cheap to fix. As for production, we have a quota. They already have a perfect means to get rid of people who are not performing. It doesn't much affect me as I don't even own a cell phone (and winning the wrongful termination case if they pulled the "it looked like a cell phone from across the room, so it is a cell phone" crap would be easy (the union has VERY good lawyers on retainer for this very reason,) but it's a transparent attempt to find justification to terminate anyone making too much money from quota bonuses and replace them with cheap, non-union workers that they can fire at a whim.
* Like many places, we use a three-point system. ALL offenses save those that require immediate termination add one point to your track. Getting caught under the new policy is a two point offence, which is worse than, for example, sleeping at your desk the entire shift.
** Our contract explicitly allows mp3 players during work because they don't have a loudspeaker system to pipe in music, and the noise from the machinery is pretty disruptive.