I first read about Diaspora project in the David Notik's blog entry. It's a student project attempting to build an open-source social networking platform. Diaspora will let users fully control and manage their own information. Initially, it started as a reaction to Facebook privacy concerns.
What Diaspora is doing is essentially an attempt to build some key components of the Platform - a simple version of the Platform Cell (user profile) and the social network. Diaspora may well become successful in building an open movement alternative to Facebook. However, it will not be able to create the Platform. The Platform is a core operating system of the internet, it should provide APIs to an array of core services, such as web browsers, storage, media content distributions systems, healthcare information management, geo-social networks, video conferencing, autonomous agent services, marketing service, payment and micropayment services. It should also provide APIs for tools that synchronize across these different services and across access devices. The Platform should be flexible and future-proof. Creating the Platform is a software engineering challenge that requires awesome resources and expertise.
Strategically, Diaspora is working towards the end user-controlled vision of the Platform, as opposed to the corporate-controlled vision and the government-controlled vision. Diaspora or a similar project could be that seed that eventually would grow into the massive global user-centric Platform.