I think you should choose a communication system that users already use, and publish results to that communication system. If those who need to be notified are regular users of Slack (or HipChat or ...), connect those Jenkins instances to the messaging app and send messages to the committer. If they regularly read e-mail, send them an e-mail. If they regularly read text messages, send them a text.
If you're feeling really novel, you could buy each person a "blink" device to plug into a USB port, then notify by changing the color or pattern of the blink device.
Mark Waite