The news caught up with George while he was still in the London. He responded on his Not A Blog, commenting on the freshly ordered third season:
Like the first two seasons, it will be ten episodes long. This one will cover (roughly) the first half or thereabouts of A STORM OF SWORDS, the third novel in the series.
I’ll be writing the seventh episode, with the working title “Autumn Storms.”
Hear Me Roar: I may be wrong, but I believe that the breakdown and writing of the third season is further along at this moment than season two was a year ago.
UPDATE: Some more pertinent quotes from David and Dan that fit the discussion and the topic of this post really well have surfaced. First, this one from a good interview posted on Westeros.org:
I don’t think anyone else asks viewers to process so many storylines and characters. And also one thing to keep in mind is that there are characters in the second book who don’t appear this season, but are coming in later. It’s just about so many new characters introduced in the second season, so we saved some for the next season. They aren’t being omitted, they’re just being delayed.
Second, the amazing Mo Ryan already has some answers from Dan Weiss that are on everyone’s mind (make sure to read the whole piece, and mind that there is a full interview coming next week after episode three):
I would say that, going forward, 10-episode seasons are really all that are possible, given our 12-month [production] cycle,” Weiss said. “For this show specifically, it’s really all we can do to do 10 of them in a year. I would say not to expect more than 10 a season any time in the near future … We had always planned on a 10-episode season [for the show's third year].
We’ve always said that we see the show as an adaptation of George’s series, not this book or that book. It’s definitely true that ‘A Storm of Swords’ is too big to even come close to fitting in one season. [...] Book 3 is definitely too much for a 10-episode season, so we’re taking the long view of the series of the whole, and trying to do as much justice as possible to George’s overall epic story and be as true to the spirit as we can, while keeping it an exciting and viable and vivid as a television show that stands on its own two legs.
A season of television needs to feel like a season of television. We have so many storylines to juggle, and they all need to ideally have a sense of a beginning, middle and end over the course of a season. Each character needs to feel like they’re traveling a specific road in the course of a season, and coming out as a different person than they went in. It’s never going to be about taking a book and ripping it in half — ‘At page 673, this is the place where [the season] ends.’ It comes down to case-by-case [decisions] with each story and how best to serve each character’s story going forward.