Insoshi - Free Social Networking Script

Insoshi is a free social networking script, funded by Paul Graham's Y Combinator investment firm, that aims to be the "MySQL of social networking platforms: free for hackers, with a commercial product for businesses." The project lead is Michael Hartl, author of the book, "RailsSpace."

Website
http://dogfood.insoshi.com/
Download
http://github.com/insoshi/insoshi