OpenPANA it'll be soon a full functional free solution which implements the PANA protocol. By now, it's a multithreading implementation, supported by a framework, which allows multiple users to authenticate.
Panatiki is a light-weight implementation of the PANA client in Contiki SO. The implementation interact well with the OpenPANA Agent. Source code has been moved to Panatiki sourceforge project (http://sourceforge.net/projects/panatiki/)