"Sean Penn often plays very intense characters that keep the world at a distance," Kilday said. "As Milk he's alternately playful and warm. At his core there is a toughness to Milk and also a lightness. That's the real surprise, that Penn captures the lightness as well."
Kilday does not believe that Penn approached this role differently than any other.
"In this case he's playing a real person. He clearly had a lot of research to draw on, a lot of footage of Harvey Milk, friends like Cleve Jones, who served as advisers," Kilday said. "My sense is both he and Van Sant wanted to make the gay sexuality as matter of fact as they could. So they introduced it right at the beginning of film and treated it as casually as the people would have treated it at the time."
While the door has swung open for straight actors to play gay roles, the reverse -- gay actors in straight roles -- is still rare, at least on the big screen.
Cheyenne Jackson, the hunky male star of Broadway shows "Xanadu" and "All Shook Up," has acknowledged that since coming out of the closet, he's unlikely to get leading man roles, though he has gotten a cameo on the NBC drama "Lipstick Jungle" and a small role in the film "United 93."
"To be frank, I think I've missed out on big parts because I'm open," he told The Advocate in April. "I've screen-tested on some really big projects, and you can't tell me that behind closed doors big execs aren't like, 'We have Dean Cain or this gay guy who played Elvis on Broadway.' I'm not that naive to think that that doesn't play into it."
But Kilday sees a shift and it's being spearheaded on the small screen.
"Older gay actors who wanted mainstream film success -- Rock Hudson being the main example -- kept their sexuality hidden," he said.
"Now you're seeing a younger generation of actors on television and stage, who [are] openly gay. Some are playing gay; some, straight. As they mature, a few over time could become mainstream A-list actors."
Those actors include TR Knight on "Grey's Anatomy" and Neil Patrick Harris on "How I Met Your Mother." Both are playing straight roles.
Still, Hauslaib believes American sensibilities are changing faster than Hollywood's. "Until Hollywood decides it will support the career of gay actors, we won't have openly gay actors," he said.
"That's the next step for our culture," Canfield said. "Where is our star who is openly gay?"