Doc, thanks for this interesting post. A couple of weeks ago an application called uPort was launched (a friend of mine is working on that project). It uses Ethereum technology and I think it has a very interesting approach towards the management of the identity (private keys), also in case that the private key is lost (It can be recover by the approval of peers). You can find the whitepaper here > https://uport.me/library/pdf/whitepaper.pdf
I hope this adds value to you and your readers.
I´m not an expert on the identity topic so I`d love to read your comments about this app.