Of course they don't guarantee what princesses are at the meals, but at our lunch last fall they had Belle greeting and Jasmine, Aurora, Cinderella (I think she is rare at Epcot meals though), and Ariel.
In Jan. 2006 we saw Ariel in her ballgown, Belle in her blue dress, Aurora, Mulan, and Jasmine. We went to lunch and really enjoyed the Norwegian food and we had lots of time with the princesses.