Tucci will be playing Dr. Abraham Erskine, the scientist who actually invents the super-soldier serum that makes scrawny Steve Rogers into Captain America. Unfortunately, it's a destined to be a small part. In the comics, Erskine was assassinated by a Nazi agent named Heinz Kruger. In true mythological fashion, it was at the very moment of his triumph as he officially presented a transformed Rogers to the U.S. military. No one was ever able to duplicate his success with Rogers.
In Tucci's hands, this could be quite a poignant moment. I wouldn't be surprised if Captain America chooses to consciously echo the death of the quiet and heroic Dr. Yinsen in Iron Man. Then again, if they choose to throw in some of the darker angles of the super soldier project (as seen in Truth: Red, White, and Black or the Clinton McIntyre "failure"), Erskine could be played as a combination of all the inject-happy scientists. He could be darker and edgier, a man willing to risk any number of lives to create the perfect man. But as we don't see a lot of positive portrayals of scientists on film, I rather hope Erskine is just a good man who is doing his part to defeat fascism. Plus, I like when Tucci plays sweet and kindly guys.