The 1.7 version of Discourse installed here includes official IOS and Android apps for your phone device. It allows you to pull together multiple Discourse sites into a single, sort of aggregated view.
I'm kind of intrigued by the idea of federated social media sites (as opposed to centralized ones like Facebook or Twitter). There isn't really a lot of inter-site interaction possible with this app. It'd be cool if you could share links or user profiles or other things across sites. This app is a necessary first step towards that kind of thing, though.