Thank you @Craig Russell for accepting me in this branch. I find Google+ great, but as Chiklu mentioned, branch offers several novel features that are worth considering.
* Your entry into a discussion is restricted, hopefully low/nil spam
* You can embed a branch in any web page.
* I think these are killer features that enable interweaving discussions among Moodle, G+, Facebook, Twitter where this is going to add value to the classroom online forums.
Link an article from web --> start a branch --> embed in Moodle --> run parallel discussions in Moodle and Branch and then compare the intensity and quality of responses. I quite like the openness, and flexibility that @chiklu just mentioned.