From Martins' Blog:

One of the hardest parts to cast was Bran. When the story opens he's a cute kid, off to see a man beheaded for the first time. But after that... think of all the challenges that await the boy in this role. We think we've found a young actor capable of handling them, however. His name is Isaac Hempstead-Wright.

From Martin's blog:

A GAME OF THRONES opens in the haunted forest north of the Wall, with three brothers of the Night's Watch on a ranging.

The viewpoint character is Will, sent to the Wall for poaching. In the pilot, he will portrayed by Bronson Webb.

He has been in projects with Tamzin Merchant, Nicholaj Coster-Waldau, and Iain Glen. One of his first roles was "boy on a bicycle." Peter Parker is Spider-Man and Bronson is a Webb, so they have spiders in common. And he has a home page, a Facebook page, and a My Space page.

From Martin's Blog:

.. yes, it's Rory McCann, a wonderful Scots actor. Most of you figured that out weeks ago, of course. Mea culpa. My clues were much too obvious this time around, especially the spelling of "porage," which yielded up the secret to anyone who googled the word. If I had gone with "porridge," that might have created a few more hours of mystery at least.