World of Warcraft cross-realm zones coming with Mists of Pandaria
In addition to fuzzy Pandas World of Warcraft's upcoming expansion, Mists of Pandaria, will also introduce a new technology that will allow you to group with players from other servers in certain designated low populated areas.
The new cross-realm zoning functionality will officially be introduced with Mists of Pandaria, but it will first be implemented in the game's beta.
With World of Warcraft being out for almost eight years, the significant majority of player population online at any given time has consisted mostly of characters at or near the level cap, Blizzard noted. This new technology, meant to alleviate problems with low-level zone underpopulation, will create phased versions of the zones that bring together players from multiple servers.
Entering these cross-realm zones will happen seamlessly just as if you were moving between any other area in the game. When in the zone flagged as cross-server you'll be able to see and play with those from your realm as well as those from other realms.
These cross-server phases will be dynamic, and based on which zones are deemed underpopulated at any given time. Looting and trading will work much the same and carry the same restrictions as if you were in a dungeon or raid with players from multiple servers
Realms will be matched will like realms, so if you're on a PVE realm, you'll only be matched with other PVE realms. Likewise with other realm types.
Check out the WoW blog for an in-depth FAQ with all of the details.