Here's a sampling - a who's who of the liberal world:
Maya Angelou
Kofi Annan
Annette Benning
Candice Bergen
Chris Brown
Kim Cattrall
Cher
Margaret Cho
Hillary Clinton
Anderson Cooper
Katie Couric
Sheryl Crow
Ellen DeGeneris
Cameron Diaz
The Dixie Chicks
Phil Donahue
Melissa Etheridge
Tina Fey
Harvey Fierstein
Jodie Foster
Jamie Foxx
Whoopi Goldberg
Jake Gyllenhaal
Neil Patrick Harris
Ron Howard
Ice-T
Jesse Jackson
Michael Jackson
Peter Jennings
Nathan Lane
Queen Latifah
Matt Lauer
Spike Lee
Ralph Nader
Martina Navratilova
Michelle Obama
Rosie O'Donnell
Sarah Jessica Parker
Sally Jessy Raphaël
Tim Robbins
Jon Stewart
Barbara Walters
Brian Williams
Most celebs are liberal, period. The fair comparison is to see if the proportion of left-vs-right celebs in general is approximately the same as the proportion of Sesame Street guests.