The World of Warcraft Test Realm Patch Notes have details on a large patch in the works to update Blizzard's MMORPG to version 4.0.1. This is part of the run-up to the release of the upcoming WoW Cataclysm expansion, as the notes include references to the Cataclysm Launcher Update, which: "allows you to stream game data while you play. This will reduce the time you spend downloading, installing, and patching World of Warcraft. We'd like to get your feedback on the toolset and gameplay experience. Please head to the forums here for additional information."