The documentation for the feature is near the bottom of the commit.
This is a really great addition. Every non-trivial Django project I've ever worked on has required extending the user model using both the bolted-on AUTH_USER_PROFILE pattern and hacked together middleware in order to support email-based logins.
While there's a bit of possible backwards-incompatibility with my hacks, it looks like this change addresses both pain points.
It's been weird to get into Django and see hacky solutions like the UserProfile/get_profile() stuff (and django-registration and South being required for most purposes), and it's great to see this make it into Django.
This is a really great addition. Every non-trivial Django project I've ever worked on has required extending the user model using both the bolted-on AUTH_USER_PROFILE pattern and hacked together middleware in order to support email-based logins.
While there's a bit of possible backwards-incompatibility with my hacks, it looks like this change addresses both pain points.