When Did Superhero Movies and Period Pieces Converge?

I’m right that this is a thing, aren’t I? First, there’s the awesome-looking trailer for X-Men: First Class, which, like Mad Men, appears to be a movie about people with secret identities living in Westchester County in the 1960s:

Now, we’ve got the World War II awesomeness of Captain America: The First Avenger, which looks terrific and cartoony-but-not-cheap in the way the beginning of Hellboy was:

I sort of wonder if this is all due to Pirates of the Caribbean, which is getting back to its period roots (I actually think part of what made the first movie effective was the sense of English gentility badly transplanted into a world where the line between natural hazards of a new colony and the supernatural were delicately shaded) by looping in Edward Teach in the fourth installment in the franchise:

Jack Sparrow legitimately counts as sort of a superhero, right? Particularly when they remember to make him competent and crazy, instead of fey and annoying?

Anyway, I’ll be curious to see if this becomes a genuine trend (Watchmen obviously has the opening credits, but the movie does take place in contemporary times, even if they’re not precisely our own). I don’t know if we’re reaching back into the past for trials that seem to require sufficiently superheroic response, or if we want the world around our human cartoons to be exaggerated and stylish as well.