The recent 2011 Cannes winners can be seen here at IMDB, a complete list

All Seventy-Eight Cannes Film Festival Palme d'Or Winners

1939 Union Pacific  U.S. Director Cecil B. DeMille

1946 Torment Sweden Director Alf Sjöberg
1946 Lost Weekend U.S. Director Billy Wilder
1946 The Red Earth Hungary Director Bodil Ipsen & Lau Jr. Lauritzen
1946 Lowly City India Director Chetan Anand
1946 Brief