I think Diaspora was crushed under its own weight. A few things I think that worked against them.
* Too much hype meant they had big shoes to fill before even writing a single line of code.
* Inexperienced team. I think they were all new college grads.
* Chicken and egg problem.
That being said, we're building federation (via OStatus) into OpenPhoto (it's already distributed). We're working with Mozilla and other yet to be announced partners. I don't think we have the chicken and egg problem.
Funny I haven't seen anyone even mention diaspora in these threads.