I just heard of this today and was like WTF how had I not heard anything of this until this point.
The series seemingly will follow the group of agents as they deal with various threats and supernatural forces. It will feature several agents featured in the previous Marvel movies including Clark Gregg reprising his role as Agent Coulson.
It is expected that there will be several cameos throughout the series by big guns such as Thor, Hulk and Captain America. But what is cool to me is that we will seemingly get to see some of the lesser known superheroes and villains from the marvel universe. Luke Cage has been confirmed for the pilot and supposedly Iron Fist makes an early appearance into the series as well.
Joss Whedon has been tabbed to direct the series which doesn't have a premiere date. But we do have a trailer for the pilot.