The Grouper Voot Connector is a jar plugin for the Grouper WS which implements the Voot spec
Note: only the operations are implemented, not the OAuth 2.0. Authentication can be anything implemented for Grouper WS and is pluggable in the same way that Grouper WS is. You can easily implement servlet container or web server basic auth without any effort.
This is currently running on the Grouper Demo Server.
The code is in SVN in the Grouper 2.0 branch (checkout, browse). The connector works with Grouper v2.0.0+. You can download the jar here.