IGN posted a description of the first trailer after the Upfronts.
Here are a few highlits:
*Most of the "EVO", which is apprently what they have called people with powers now that their existance is public knowledge.
*Noah Bennett claims he is just a paper salesman, and someone tries to convince him to help. He gets an envelope with a pair of horn rimmed glasses in it.
*They showed files on familiar characters from the first season, including one labeling Mohinder an EVO terrorist, and a memorial for Claire.
*Zachary Levi's character is a bad guy, and they showed him and a woman shooting a whole room of possible EVOs after giving a speech about their powers being dangerous and unnatural.
*They showed Future Hiro, and the Haitian
*A new character had a big metal ball attatched to his wrist. He cuts off his hand and flies away.
*Another new characer, Miko is seen holding a box with a sword in it.
*A masked ninja like character is briefly glimpsed.
*It eneded with a woman saying This happened faster than we thought. I don’t thin I can control it much longer. The sky behind her then turned into an image similar to the Heroes logo.