The big advantage is that users won't have to be 'trained' for anything new: they are all familiar with email / password signups. It's pretty obvious that the

The big advantage is that users won't have to be 'trained' for anything new: they are all familiar with email / password signups. It's pretty obvious that the website will use your email so no privacy surprises. Switching between email identities is a snap. It's actually pretty pragmatic approach given that what most people do is first assess the website risk, choose whether to give their primary or secondary email (but wait which one? i have 5), type it in (what if they mistype / remember the wrong one) and then type one of their 3-4 rememberable passwords. If anything, browserID neatly simplifies the authentication process for the user. Also, developers only have an assertion to send; that's really really simple and less likely to break in future releases. Easier signups are important especially for small web utilities that just need a unique identifier and not much private information to work.