One of my favorite issues! My company builds community tools for gamers & game developers. I end up thinking about and dealing with these issues a lot.

Mobile communities are a completely new frontier. Frankly most of the technology is poor. The vast majority of mobile communities have been ported over from long standing web technologies.

In terms of moderation there has really been a paradigm shift away from handling it through volunteers or employees toward hiring professionals. Many firms have sprouted up to fill this void. You'll see publishers, marketing firms, PR firms, and agencies offering community management/moderation as part of their suite. There are also firms that exclusively handle this.

I could dig into this issue more with some more details. Community management is a giant topic that has really exploded recently.

I'll recommend lighthouse.io which is a community about communities!