Apparantly, there was a solid casting rumor at Comic Con. I got this from ComingSoon.net:
John Barrowman, the star of "Torchwood," was just asked moments ago at the San Diego Comic-Con panel if there was any possibility that he would be playing Captain America in the upcoming feature film.
He smiled and gave the stock answer that he'd love to play the character and that Captain America has always been his favorite comic book superhero. Clearly, though, the notion did not take him by surprise and he ended up admitting there had been discussions with his agents and meetings on that very issue.
Personally, I'm still rooting for Thomas Jane.
Also, The First Avenger: Captain America looks to have a May 11, 2009 release date. But I'm sure you all knew that.