Quote Originally Posted by viion View Post
You can even download Blizzard's updates while playing the game lol unlike XIV's paranoid "You have XIV already open!"
Exactly. Blizzard's patcher allows for both pre-downloading and letting you log in before it's finished.

Source

In the upcoming expansion World of Warcraft: Cataclysm, the launcher will be updated to "stream" installation and patch data. The new launcher is broken up into three stages of download progress:
  • SETUP (RED): Core game, or 5% of content, is being prepared. You cannot enter the game at this time.
  • AVAILABLE (YELLOW): Base game, or 70% of content, is not completely applied. You can play, but your game experience will not be ideal. You should ideally have 1 MB/sec or better when choosing to play.
  • PLAYABLE (GREEN): Extended, or 25% of content, is almost complete. You may begin playing at this stage with few game issues. You should ideally have 1 MB/sec or better when choosing to play.
The Updater and Downloader have been integrated closely into the Launcher, resulting in less application switching when patching and installing.