The HBO schedule confirms that there will be a two-week break between the eighth and ninth episodes of the third season. This is due to Memorial Weekend, a big holiday in the USA. Last year the show suffered a significant ratings hit on this weekend, so HBO have opted to instead air a TV movie in the Game of Thrones slot and resume a week later. I'm also hearing there will be significant marketing coverage for the episode, similar to how "Blackwater" was trailed last year.
Slightly irritating since the UK and all other territories airing episodes close after the American broadcast, where Memorial Weekend doesn't even exist, will also have to wait an extra week, but not the end of the world :)