At the World Economic Forum in Davos, Switzerland, Facebook CEO Mark Zuckerberg revealed some data about the site's growing mobile usage (summarized by AllFacebook):
As I've said in the past, the iPhone app has made me a much more active Facebook user across the board.
Meanwhile, last week comScore released some new data showing strong growth for mobile social networks in Europe:
In our past research, we found a year ago that 6% of respondents (n=789) in the US had accessed social networks from their mobile phones. The top networks were those that they used online, namely Facebook, MySpace, etc. The number today in the US is probably closer to 9% or so, consistent with the UK -- although the US is a much larger market.
If you look at the Opera data, social networks such as Facebook are always among the top sites visited. However mobile-only networks will have extreme difficulty competing with those that have established usage on the PC. A few may survive and/or be acquired but most will have to modify their content and emphasis to remain viable.
Social networking unlike some "verticals" is a winner-take-all segment, with only a few sites able to compete at the level of scale necessary to succeed.