[enaeseth]

Online login services are generally many-to-one. For example, many sites accept Facebook login, but for a user to log in that way, there is only one identity provider they can use: Facebook. If you don't have a Facebook account, or don't want the site in question to have any access to it, you can't use Facebook login.

When the article says "distributed", it means Persona is many-to-many. Any domain can implement the protocol, so when a site accepts Persona login, you can choose from many identity providers – including your own, if you're industrious and want to set one up for your domain. Most people are using Mozilla's service today, but the idea is that email providers like gmail will implement it themselves in the future.