Besides the iPhone and whenever Google sneezes, Facebook continues to be the talk of the town, at least in the echo chamber of Silicon Valley. Let me give you a simple example of why Facebook merits attention, besides Dennis Howlett's post yesterday on how Facebook could play in the enterprise.
Take Facebook Carpool, an application from Logan Green and Rajat Suri. It's green friendly and the authors of the app state the mission as "reducing the barriers to a mainstream ride-sharing culture, where everyone can find ride-sharing partners in an easy and safe way." You can view ride sharing in your network, search for rides, submit requests, track miles, check Google Maps and check profiles of carpoolers.
Facebook Carpool is a good example of how social networks as a hub for applications creates some powerful effects. Identity, reputation, relationships, connections converge in this environment and allow for more efficient and transparent transactions, such as ride-sharing.
In addition, Facebook promotes a more social development environment, not unlike open source. The authors of Carpool receive feedback on how to improve the application from users who are part of the network on a discussion forum. Social applications engender a more social approach to developing applications, which increases the likelihood that applications meet the needs of users and not just the designers and engineers.