In an interview with Iron Man 2 director Jon Favreau talking about Stark Expo in the film at the Los Angeles Times, a spoilerish bit reveals how the Expo is also mentioned in Captain America:
The filmmaker said that the fabricated history of the Stark Expo will echo in other Marvel films, too. "It does figure in to the other films because in the Captain America movie you’re going to see the early one, which I think is a lot of fun," Favreau said. "They’re going to have a reference to Tony’s father, Howard Stark, played by John Slattery, and his earlier Expo. But I don’t want to say more than that."
Meanwhile, Entertainment Tonight has posted a featurette on how Scarlett Johansson got in shape for Black Widow:
Source: Los Angeles Times, Entertainment Tonight