ET has the details...Fifteen of the 20 stars nominated for acting Oscars could end up mingling in Beverly Hills on Monday at the Academy's Nominees Luncheon. Anne Hathaway and Sean Penn are two of the A-listers expected to attend. Read on for the rest!Sean, Anne, Richard Jenkins, Frank Langella, Mickey Rourke, Melissa Leo and Kate Winslet are the Leading Actor and Actress nominees expected at the luncheon.Supporting Actor and Actress noms Amy Adams, Penelope Cruz, Viola Davis, Taraji P. Henson, Marisa Tomei, Josh Brolin, Robert Downey Jr. and Michael Shannon might also attend.Catch the 81st Annual Academy Awards February 22 at 8 p.m. Eastern on ABC.