Currently there are only 2 types of communication preferences that Rock uses in groups, Email and SMS. I propose adding Push Notification to these options. This option would need to be conditional depending on if a person has the mobile app(maybe it's only shown on mobile blocks?), additionally it could be restricted to certain group types(i.e. communication lists).

Use case: You have a Subscription list that sends out a "Daily Devotional" link that people can subscribe to. This daily communication uses a communication template that is configured with all three communication mediums(Email, SMS, Push) to send out the communication. If a person could choose Push Notification and the comm template is set up to link directly to the devotional. It might make this the easiest method to consume content. Tap the notification and it opens the page... eazy peazy... unless your that person with 20k notifications...