**ALERT**
World of Warcraft Patch 4.0.1 has hit the Public Test Realms.
Server Status: Offline
The Character Copy page is accepting transfers, however it won't work at the moment as servers are not yet online. Please wait until confirmation before attempting to transfer your characters, lest they get lost in the Nether.
The new and improved Cataclysm Launcher is now available for download. You may need to download this launcher from scratch. Be warned however that the client weighs in at 15.6 Gigabytes.
For US/Oceanic players: http://www.worldofwarcraft.com/ptr/
For European players: http://www.wow-europe.com/ptr/
The new launcher in action: http://img9.imageshack.us/f/ptrlauncher.jpg/
The initial updater has a habit of sticking at 4% for a while too, this is normal. It will eventually skip to 100% and start the download process.
The updater seems to be a little buggy, don't be surprised if it acts extremely odd.
If you are getting a message stating "The installer does not need to be applied. It requires a version of "Wow.exe" older than 4.0.0.12635, but you already have version 4.0.1.12942.", your Cataclysm Beta installation is conflicting with your PTR installation attempt. You can rename the Beta folder to something else and it should allow you to install the PTR.
One last thing, you should let the launcher update non-stop until it finishes, and make sure to run it in Administrator mode. There is a chance it may lose data if you try to play the game when it's not completed, and you may have to re-download gigabytes of data, and I found out the hard way that if you don't run it in Administrator mode, it can get stuck at the very end of the 'Available' section and keep downloading data, but not actually apply it to the installation.