During pre-production of any movie there is absolutely no shortage of creative ideas, story boards and animatics that end up unused; however, it is not uncommon for some of those unused ideas to show up later in films that are a part of a series. In that vein, it's quite possible that the inception of the MCU Ultron in Joss Whedon's coconut may have happened during pre-production of the Avengers.
In this animatic we see Tony Stark doing a little work while JARVIS seems to take on a little different personality, one very familiar to those of us who know the way Ultron looks at humans. Now, I'm not claiming JARVIS will evolve into Ultron but I think that this idea carried over into Shane Black's Iron Man 3 (Three-Disc Blu-ray 3D / Blu-ray / DVD + Digital Copy)
and will come to it's climax in Avengers: Age of Ultron. We say Tony's suits becoming sentient and acting according to his brain activity...the next step is the AI behind the suits continuing to evolve and doing what they want to do: that's Ultron folks. Even if Pym isn't behind the design, the idea of AI evolving and taking its own direction is the foundation of what happens with Ultron (and Skynet..dun dun dun dun dun). 