A rillettes is an old world way of preserving meat that is slowly cooked in it's own fat and then covered in that fat to seal it from contaminants in the air. Traditionally rillettes are made with pork but other meats are also used as well.
You really gotta get one of Thomas Keller's cookbooks. This salmon rillettes is a mixture of smoked salmon and steamed salmon that has been marinated in Pernod, white pepper, and salt. The salmon spread is so delicious you'll want to keep this stuff around all the time.