[zamadatix]

Aruba, Cisco, Extreme, Mist, Ruckus. The first I saw use it was Aerohive (now part of Extreme) and it took the enterprise market by storm about 5 years ago. For most enterprise deployments 802.1x (either username+password or certificate) makes more sense but once you get into BYOD land (say, senior living) not all devices support that (say an Xbox) but you still want to give a user a way to connect anywhere they go not just their main living area. Similar with the BYOD network on schools, give out the PSK to anyone staff and a year later the kids all have it and you have to change every PSK only device to a new PSK manually to fix it. Use multiple PSKs to give different groups of devices different PSKs, and even different staff different keys, and you not only contain the problem but can actually narrow down on the worst leak offenders as well.