I'm glad this discussion is happening, in my mind a couple of things need to occur
1.
angularjs.org site encourages users to post questions there and states purpose for angular googlegroup
2. when new problem solving questions come in, kindly ask poster to post it there with tags, angularjs (at minimum) and then maybe one other like 'directive', 'ngResource', 'services' etc.
3. people watching gg posts hopefully will turn attention to stackoverflow. I do know that core devs are watching for posts.
-my 2c
--dan