WSGI Middleware for OAuth authentication
Flask has an OpenAuth extension that's written by the Armin Ronacher (Flask's author). It provides Flask with support for Open Auth 1.0.
You should take a look at repoze.who, which is authentication framework for WSGI application with plugins available for:
If you're looking to authorize clients against facebook, why not use the python sdk they provide that includes an oauth interface found here https://github.com/facebook/python-sdk.