The D-NET researchers from INRIA have ported Contiki to their WSN430 platform as part of the SenseTools project. They have written a great introduction to Contiki that is well worth a read by anyone interested in how Contiki works. They have also gone through a number of Contiki examples with excellent walkthroughs.
For more tutorials on Contiki you can follow the following link:
Two Contiki Summer 2009 Tutorials - SICS