The show stars Clark Gregg, reprising his role as Coulson, with Ming Na as Melinda May, and Brett Dalton as super-spy Agent Ward, a black ops expert almost as skilled as The Black Widow. Cobie Smulders, who played Agent Hill in The Avengers, is slated to reprise that role as a recurring character.
The conspicuous absence of Iron Man, Captain America and the other member of the Avengers is easily explained given that that group of superheroes saw him die at the hand of Thor's brother Loki, and don't know he's alive.
What is particularly awesome about this show is that it's written and directed by Joss Whedon, the man responsible for The Avengers, as well as TV shows Buffy the Vampire Slayer, Dollhouse and Firefly. He's famous for creating highly original characters with great depth - even the bad guys.
Here's hoping the show is shown here before the next Avengers movie!