At the moment oAuth2 Connect allows you to authenticate with different 3rd party oAuth2 providers and maintains association between drupal uid and provider uid.
It's currently available for Drupal 6 only.
Here is the link which summarizes differences between oAuth1.0 and 2.0
http://blog.apigee.com/detail/oauth_differences/
The module provides an abstraction layer with pluggable components for different oAuth2 providers. Currently it doesn't have an UI and all oAuth2 configuration is done with plugins ( and plugins are just classes extending an abstract class ).
The goal was to allow the plugin to handle the dirty work ( dialog url creation, tokens manipulation, user data retrieval ), because each provider implements the protocol a little differently. Most notably Facebook requires post request to get the access token.
We tested the module with the following oauth2 providers:
- Twitter
- Facebook
- Yammer
The main ideas behind this module were simplicity and extensibility. Before creating this module I evaluated different options including oauth and oauthconnector but at the moment there was no Drupal 6 version with oAuth 2.0 support, only 1.0. There were also many dependencies to consider - oauth, connector, http_client, chaos tools.