PHPeople is a small skeleton of a php/mysql based social network; I did it as my diploma project.
It will feature sharing statuses and messages even with attached images, comments and "likes" on the statuses and known people management.
Open source project that offer summary and download services on this page is a project that carry out their development work on other open source development sites. Their work is linked to this page via a feature called OFI, and their work is not carried out here on OSDN site.