[foobar456]

OAuth is for authorization, not authentication. Please stop using it like this. If you want SSO-style authentication using OpenID or SAML2.

[qu4z-2]

Unfortunately I think that ship has sailed. Personally I'm hoping Persona will catch on. At least that's designed as an authentication scheme.

[foobar456]

What problem does it solve that OpenID doesn't? OpenID already has a lot of adoption, and IMO works quite well.

[qu4z-2]

OpenID is great, but I somehow just don't expect it to get that much adoption on sites where "Sign In With Facebook" is the default. Whereas I have at least some hope that Persona might become that common if Mozilla play their cards right.