If you've read the books and plan to post a comment that gives away something that has not yet been aired on the television show, please use spoiler tags.
Onward to today's season 2 news: Natalie Dormer has been case as Margaery Tyrell. (Minor not-really-a-spoiler-but-some-might-quibble in the link, stating a tiny bit about Margaery's role). I'm not familiar with the actress, but apparently she had a well-liked role in the Tudors, and will be appearing in Captain America, as well.
[Edit: Season 3 thread is here.]