Cell phones are permitted in the Media Center at GHS for any use except talking on them as that tends to get too loud. Students use them for work, to text, play games, listen to music (with earphones), and watch movies (also with earphones). If the students are being too disruptive regardless of their cell phone use, we ask them to quiet down and if they continue to be a problem, we ask them to leave the Media Center.
Lots of our teachers assign "tell me about yourself" assignments at the beginning of the year using either a Google Form or an online discussion board so students absolutely use their cell phones to complete those assignments (as well as complete them using iPads, laptops, or desk tops) - using a device is the only way to complete those types of assignments.
At our middle schools, students must keep their cell phones in their lockers during the school day so cell phone use should not be an issue when they are in the Media Center. However, we are a one-to-one district - every middle school student now has a Chromebook so they can do many of the same things that they do on cell phones on their Chromebooks (IM, take pictures, play web-based games, etc.). So the same idea would apply - there are consequences for being disruptive regardless of whether or not their disruptive behavior is due to technology use.