The Hobbit gets green-light and announces February start

[Mister Underhill]

Here's what Jackson said about the dwarves at Comic-Con this summer:

Originally Posted by PJ

We always wanted to retain the thirteen dwarves that Tolkien wrote about. It’s not wise or sensible to be mucking around with that degree of Tolkien lore. So we have thirteen dwarves to cast — it’s going to be a lot of fun. [Laughs] There’s thirteen poor guys who are going to be walking around the mountains in summer wearing big, thick costumes and sweating under their prosthetic makeup. It’s gonna be tough — very, very tough. It is logistically very difficult. You imagine getting those guys through wardrobe and makeup at the beginning of each day and then having them ready to shoot and they’re gonna be passing out in the heat. It’s gonna be tricky. Some of the dwarves are obviously more important than others. We’re isolating about four or five of them to make them the key dwarf players and then the others will be more supporting roles.

Which is fair enough and more or less true to the book -- let's face it, not all thirteen dwarves have a featured role. I imagine that they closed the Martin Freeman deal and wanted to make the announcement right away with what cast they already had. Deadline Hollywood has a few more speculative names that are rumored to be in negotiations (including Bill Nighy for the voice of Smaug).

They don't have a Balin yet as far as I can tell. He's one of my favorites and seems an obvious one to be a more prominent dwarf.