I added the ability to sign into this site to comment with Mozilla Persona. Not that I'm expecting people to use it, I've only had a handful of genuine comments since I started the site some years ago. I was just interested in trying it out, which is why I have this site.
It was pretty straight forward as I already only support the concept of signing in with 3rd party authentication providers such at OpenID, Google and Twitter. Adding Persona was just adding another provider, I didn't need to change how the authentication system works. Here is the commit.
Another thing I liked is OpenID. I understand it had usability and adoption issues. With OpenID though, I could choose who manages my identity or I could manage it myself. Apparently an email provider (in my case, me) can implement the Persona (BrowswerID) protocol and not depend on login.persona.org. Perhaps that is something I will look into after posting this.
Finally a note on adoption; I was having dinner with Özlem last night and tried to explain Persona, but was unable to convince her to even try it to sign into this site. To be fair it's only a sample size of one and I think Özlem was hoping dinner conversation wouldn't be about online identity management.