There are two aspects to the Ripple project: the development of the protocol and its implementation as a back-end server, and the development of the Ripplepay.com site and the Ripple web service front-end.
The core of the Ripple project is the protocol that will allow peer-to-peer hosts to manage mutual credit accounts and search for paths of payment intermediaries. The protocol specification will evolve as implementation progresses.
The latest protocol design can be found at the protocol development wiki.
The protocol development discussion takes place on the SF project mailing lists, mainly the ripple-protocol list.
We're developing a standalone (non-protocol) server to refine the client API/protocol. It is called ripplebase and is in a git repository at http://github.com/rfugger/ripple/. This is under active development.
The latest protocol implementation prototype code (in Python, using the Twisted networking framework) can be found at the subversion repository at http://svn.ripplepay.com/ripplep2p/ (to view with browser, login with guest/guest – svn read access is anonymous). This work will be the basis for adding inter-server protocol support to the standalone server above.
Ripplepay.com is a fully functional standalone Ripple system, without any distributed protocol back-end that communicates with other servers. The service is free to use. Eventually, when it is ready, the distributed protocol back-end will be integrated into the web-service front-end. For now, all transactions must occur between Ripplepay users only.
The code is available as a Django application called RippleSite at the sourceforge project site so anyone can run it on their own server. The latest code (upgraded to Django 0.95 but not fully tested) is in the svn repository at http://svn.ripplepay.com/ripplesite/ (to view with browser, login with guest/guest – svn read access is anonymous).
Users of the Ripplepay service have a discussion forum at the Ripple Users google group.
Please if you're interested in helping out with the project.