World of Warcraft will allow cross-realm raids with patch 4.3.2, Blizzard has announced. Players can already form cross-realm parties with Real ID friends, which serves as the backbone for the new raid functionality. It will also let you use the Raid Finder and jump into any classic dungeon or raid to automatically join an instance.
The announcement notes that you won't be able to run normal or Heroic Dragon Soul with these types of raids yet. A separate patch notes post mentions assorted class balance fixes, and general minor fixes. It's already available in the public test realms, and Blizzard invites players to give feedback on the test realm forum.