Thanks, this is why I read all the bad comments on HN: in hopes of seeing a very informative one like this :)

I'll just point out that this:

> The Graph Stores do seem to play better with Java.

was likely a dealbreaker for Diaspora, since they were a small team without, I'd assume, Java experience. Also the nature of the project virtually requires an open-source database so Stardog would've been out. With SQL you have not one but several free and open-source implementations that are battle-tested and work well with just about any programming language out there. That makes SQL a better choice for many projects even if a graph store would map more neatly onto their problem domain.