I just finished implementing BrowserID in an application that I am building. It is quick and easy to use. Perhaps 20 minutes to get it to work. I used OpenID before. OpenID is annoying and difficult. I spent 3 full days working on it.
I'm really excited about BrowserID. I think for the end user it makes more sense than OpenId which was doomed from the start because it was too difficult to understand what it was.
If only people owned their email addresses then this would be a truly decentralized (eventually) and portable identity system. I do think emails are the best global handle for users that we have currently - we should treat it as such.
I actually talked to Lloyd Hilaiel from Mozilla who worked on BrowserID and it's currently in alpha and they hope to move it to beta in a couple months. At that point they'd be committing to keeping it around.
The web needs this to be widely adopted. They've got some unique challenges to make it easy to integrate and easy to understand but I think they're on the right track.
OpenID kinda scares me, security wise. There's too many ways for developers to screw it up. Witness the ones who used Facebook names as unique user identifiers.
At least with email, provided by the email host, the string you get from them will be unique.
