We actually knew this, but Paul Bettany has made it official on a late night talk show - he's playing The Vision in The Avengers: Age of Ultron. It's interesting that this leaked and became so well-known, because The Vision's appearance is sort of a spoiler. You got spoiled!
Bettany reveals very little else about the character in the movie, except to say that Joss Whedon has picked and chosen which of The Vision's powers to bring to screen. He definitely flies, I can tell you that much. And I can also tell you this: the picture of The Vision that Jimmy Kimmel holds up is very similar to what The Vision will look like in the movie. Yes, they've gone colorful and caped, at least according to my sources.
My favorite bit from the above interview is this, where I think Bettany makes clear his real feelings on playing the role:
It’s very exciting for me, but everything is a double edged sword, right? Because I was playing J.A.R.V.I.S. for years and my job was I would turn up at a recording studio for 45 minutes, do all my stuff, and then they would give ma huge bag of cash and then I’d go home. Now it turns out they’ve found me out and they want me to actually do something!
It's a joke... sort of. I know that Bettany LOVED this job when it was easy, and now it'll be anything but.