The new test realms for 2.0.7 are now online for everyone that wants to help out with testing the upcoming changes. You can find more details in Blizzard's information posted here:

The 2.0.7 Public Test Realms are now live and we invite all players to help test the upcoming changes by copying characters and downloading the PTR client. You can find the most current 2.0.7 patch notes here: http://www.worldofwarcraft.com/patchnotes/test-realm-patchnotes.html

You can begin copying your characters and downloading the 2.0.7 client through Account Management here: https://www.worldofwarcraft.com/ptr/

As always please use the Test Realm Forum for any reports of bugs or issues with the patch being tested, as well as any conversation concerning the PTRs.

Test Realm Forum: http://forums.worldofwarcraft.com/board.html?sid=1&forumId=11572