Facebook operates on a lot of open source software.
The best thing diaspora can do is to take a look at that open source facebook release - and just run it on a server - add some federation functions, and voila, a prototype primitive facebook and twitter killer with a lot of potential
In fact, maybe I should do such a thing..
I want to live in your world.
Because you make it sound awfully similar to the "StackOverflow in a weekend" episode:
Facebook Open Platform is a snapshot of the infrastructure that runs Facebook Platform. It includes the API infrastructure, the FBML parser, the FQL parser, and FBJS, as well as implementations of many common methods and tags.
Design work will need to be done from scratch. But I think there's some good basic structures in there.
there's nothing wrong with green field dev. especially in this case. fairly sure slapping on some 'federation functions' would result in a hell of a mess.