I wanted to run my own social networking site just for me and my friends using a FOSS project, so I was excited about Diaspora, then I saw that it requires Node.js. I have no interest in setting my server up for that. I imagine this selection was made because developers think Ruby is cool and PHP is boring and lame. Unfortunately, whatever the justification was, to make Diaspora work you need to have, you know, Diasporas, but if the only people using the project are those that manage their own Node.js server, then the already puny market size of available Diasporas has just shrunk by several orders of magnitude. It really needed to be a project that could be installed on any generic LAMP server, but the developers are so rarely interested in this boring aspect (this is actually the case across many engineering fields, it's why companies hire marketers) that left to manage their own projects they fail to achieve their stated goals.
So I took a look at GNU Social, which is written in PHP. Unfortunately, they also fail the marketing test. The project seemed to revolve around making a 'federated' social networking system. However, the actual features of the social networking seemed to be trumped by trying to make the federated system work. From a marketing perspective, they put the cart before the horse. How many users want a circa 2009 facebook clone? I bet a fairly high number, but GNU Social doesn't even offer that level of functionality. The 'federation' of the system should be viewed more as a distribution element, so, you know, before going to distribution, you should have a product that people want to distribute, and GNU Social is not that.