There's talk in some media outlets that Cardinal Sean O'Malley of Boston is papabile.
I don't believe this will be the case however. First, he is a member of a religious order. The Last Pope with religious orders was Pope Gregory XVI who reigned from 1831-1846, he was a member of the Camaldolese order (a branch of the Benedictine order) and was a monk. So it has been some 166 years since a religious has reigned as pope.
Second, The American church has been rocked by the Sexual Abuse Scandal. While Cardinal O'Malley may not have been directly involved in any of the scandals his predecessor in Boston was Bernard Cardinal Law, which we know was involved in alleged cover-ups of the abuses taking place. It's important to note that Cardinal O'Malley has settled over 101 abuse claims and has stated that he initiated a zero-tolerance policy agaisnt sexual abuse in his Archdiocese. He is also responsible for the first comprehensive sexual abuse policies in the Church. In 2010 he was named the Apostolic Visitor to Dublin and is overseeing the response to the sexual abuses in the Archdiocese of Dublin and its suffragan dioceses and reporting back to the Holy See on the progress to appropriately handle the abuses there.
Thirdly, he's a relatively new cardinal, joining the college of cardinals in a consistory in 2006. He is also fairly young coming in at only 68 years old. I don't believe the cardinals (an overwhelming majority Italian) will want to have an American with a long papacy, and O'Malleys could last 15-20 years.
I also don't believe he has garnered a name for himself, outside of dealing with the sexual abuses here in the states and in Ireland, I really don't hear much about him.
Out of the other cardinals from the United States, 11 of which are able to vote in the consistory (the 2nd largest group with 10% of the voting power) the only one I think would be an absolutely amazing pope would be Timothy Cardinal Dolan of New York. In his short rise to national attention after taking possession of his See in the Archdiocese of New York in April of 2009. He was elevated to the College of Cardinals on February 18, 2012 with 21 other new cardinals, which puts him in one of the youngest classes of the College.
Cardinal Dolan has served as the Rector of the North American Pontifical College, as Bishop of St. Louis, as Archbishop of Milwaukee (where he concurrently served for a time as the Apostolic Administrator of Green Bay) and finally as Archbishop of New York. He also serves as the President of the United States Conference of Catholic Bishops. Cardinal Dolan is one of the strongest voices for the terrible health care crisis that is being pushed down the throats of Catholics in this country by the federal government.
Should he be elected, however, I think he would almost instantly be known as the "Laughing Pope" or the "Smiling Pope." That's not all he has to offer though, he is also a wonderful theologian and is amazing witty and light-hearted at the same time. If we did have a Pope from this side of the hemisphere he would definitely be my number one choice. However, this too is unlikely because of his lack of time being a cardinal. Also, again, his youth I believe will be a downfall to the electors as he is only 63!
So an American Pope? No, probably not. The faithful in America still have some time left, in my opinion before we can expect an American to rise to the seat of Peter, but with the Holy Spirit anything is possible.