Modern web UI is nice, but at the end of the day when it comes to mobile, apps are still king.
If the purpose of this is to replace the interaction we had on Yammer, a mobile app is a necessity...
I was curious about this as well, so I checked and the software that this site is based on (Lithium) doesn't support mobile apps, after focusing on a responsive design instead for the last few years. However, they have introduced an Android SDK which went GA in May and an iOS SDK is on the cards as well, so mobile apps for the Microsoft Tech Community might be much more likely/practical at that point, wouldn't that be good?