Scarlett Johansson sheds some details.

One aspect of this big Marvel Movie onslaught I never considered is chronology. When do these films take place in relation to each other? We know how long Iron Man 3 takes place after The Avengers, and the Agents of SHIELD TV show clearly takes place after that as the first episode featured some of those glory-face-bomb guys.

According to Scarlett Johansson (in an interview with Refinery 29), Captain America: The Winter Soldier will take place two years after The Avengers, which means it will basically match the amount of time gone by since the film debuted. If they keep this going, that means Age of Ultron should take place three years after the first film. I can't tell if it's weird or awesome that the Avengers is a supergroup that only gets together a couple times a decade.

She also goes on to discuss Black Widow and Captain America's relationship in the film:

By a series of unfortunate encounters, they will be in a situation in which their friendship becomes more intimate. They share many similarities because they live on the defensive without relying on anyone. Also, the two have been working for the government throughout their professional careers. With their friendship they begin to question what they want and what is their true identity.

Did you hear that? Black Widow's going to take Cap's virginity! Good for him!

This isn't really news, but it's fun. And while we're at it, here's a quote from James Spader about why he's eager to join the Marvel Movie Universe (via The Independent):

I think it’ll be a lot of fun and it’s incredibly nostalgic for me. When I was a kid my best friend had trunks of comics and I didn’t have any so I used to love going for sleepovers at his house. Also I have three sons and two of them have a great interest in comics so they’re excited I’m playing the role.

We need to figure out which of James Spader's three sons is such a jock about comics and ask him what his deal is.