I am damn excited about this, I love George R. R. Martin's Song of Ice and Fire books. HBO greenlights the show, and here's the the full cast.
I had a feeling that's who they were going to go to for Tyrion Lannister, I hope he does a good job. When I read that Lena Headey was cast a few days ago I just assumed she'd be Catelyn Stark, but I'm sure she'll be a good Cersei. I'd say they cast Arya Stark well, at first glance I could've sworn that was a boy. Not sure about Mark Addy as Robert Baratheon, he's certainly got the belly girth but I imagined him as a more imposing figure. Ah well, hope he proves me wrong and kicks arse.
No Stannis or Renly I notice, were they in the first book? Can't remember.