It's really great that you're adding this feature. Several questions on the scope:
1. Will you support the use case where authentication is done via the social provider and spring security is used mainly for authorization - that is no local signin/signup. I have been struggling with this issue and the few discussions that I could find on the internet suggest using a fake password field in the database, which is hacky and I would like to avoid. I was implementing my own authentication provider which skips the password check, inspired by your approach in the greenhouse, yet now I'm considering waiting for 1.1.0.M1, since it's due in a few weeks. However, would you please let me know if this use case will be covered by the ongoing implementation.
2. I second the need for supporting Remember Me functionality. I haven't been able to figure out an approach on how to go about this looking at any of the spring social samples or the greenhouse. Will this be included?
3. How would the integration address other issues such as session management while supporting multiple providers? For example, would it support detecting concurrent sessions by the same user signing in via different providers? How about detecting and merging multiple provider accounts belonging to the same user?
Thanks again for your efforts and the great code.