UbiRazz, a UK Community Manager for Ubisoft, has announced on the forums today that an update for Assassin's Creed on the PLAYSTATION 3 has been made, and you should be able to download it today, or within the next few days, depending on your location. His full post.
"Following consumer feedback regarding some issues while playing Assassin’s Creed for PlayStation 3, a corrective update has been developed and will be released worldwide on the PLAYSTATION® Network over the next few days. You can proceed to installation simply by launching your Assassin’s Creed game. Please note that release times of this update may vary depending on your location. Thank you again for your patience."[Via Ubi Forums]