We already knew that Sam Rockwell was playing Justin Hammer, and it was obvious from casting that there would be a different spin on Tony Stark's business rival - but today we get our first bit of insight into director Jon Favreau's approach to the character.
Rockwell told MTV News:
"They wanted to go with a rival for Tony Stark who is closer to his age, and make him American"
OK - so maybe it's not really insight but just confirming what we thought. :-P
In the Iron Man comic book series, Justin Hammer was British and as evident in the image above, much older than Stark (go here for his comic book bio) and he ends up taking over Tony's company and turning it into Stane International. He stole the Iron Man tech and sold it to a number of super-villains, thus setting up the classic "Armor Wars" story line, in which Tony goes all out to retreive all the stolen technology.
Rockwell went on to say that his character is brains and not brawn, and will not be donning any sort of super-powered armor in the film. Also, there's a lot of improv going on in the film, which at first made me nervous - but if I recall the same was said about the first Iron Man movie.