[Django]-OAuth web service and Django-piston

I’m in the same-ish boat (implementing an API with OAuth authentication), and I came across the django-oauth-plus project in my research. The tutorial does a good job of walking through each step of the process outlined in the diagram you linked to. The code itself seems a pretty complete implementation of OAuth (not sure if I know what I’m talking about tho, just learning this stuff).

Also, this guy has a pretty great tutorial about the basics of OAuth (I struggled with that).