From phone calls to SMS, mobile devices have deep roots in communication. So it's no wonder that people use them to talk to each other -a lot. In fact, this behavior is so dominant it could become "law".
Jamie Zawinski's popular Law of Software Envelopment states:
Every program attempts to expand until it can read mail. Those programs which cannot so expand are replaced by ones which can.
I think this could be restated for mobile applications as:
Every mobile app attempts to expand until it includes chat. Those applications which do not are replaced by ones which can.
- Apple's iMessage delivers over two billion messages per day. (source)
- Japanese chat app, Line, took only 399 days to reach 50M users. That's 3x faster than Instagram. (source)
- Snapchat, the impermanent messaging app, now sees 60 million snaps sent per day, and users have sent over 5 billion snaps in total. (source)
- When mobile networking app Path added private chat, in the first 24 hours it made more money than it had in its entire lifetime as a company. More than 1 million messages sent by users within the first 24 hours . (source)
Mobile Social Networking
The bigger idea here is that what works on the desktop does not necessarily translate directly over to mobile. Consider the case of Path, which essentially created a mini-version of Facebook in its first few iterations. That may be a decent social networking experience on the desktop, but a mobile social network looks more like a combination of chat & photo sharing, which is what Path just iterated to.
Google+ take note. You have Android, Google Chat, and Hangouts. The pieces are there for a mobile social network at the OS level, not just within apps.