It's always unfortunate in World of Warcraft when a friend chooses, for whatever reason, to play on a different server than you. However, 1up spotted that Blizzard is now working on a feature which will allow you to reunite with your chums on any server to slay monsters together.
A post by World of Warcraft community manager 'Nethaera' on the forums explains that a "cross-realm Real ID party system" will allow players of the same faction on any Realm, who are Real ID friends, to party up and queue to play 5-person regular and Heroic dungeons together.
While friendship is free, playing with friends will not be entirely so.
"It's important to note that as with some of the other convenience- and connectivity-oriented features we offer, certain elements of the cross-realm Real ID party system will be premium-based, though only the player sending the invitations will need to have access to the premium service," the post explained.
As the cross-realm party system is mostly a mystery for now, it's unsurprisingly unclear exactly how usable the feature will be if nobody in your party has paid for the premium service.
Blizzard promises more details "as development progresses" and notes that "certain elements of the feature" may begin to appear on the Public Test Realms. "As this is a fairly complex service to develop, we don't have a release date to share quite yet," it explained.
World of Warcraft already offers cross-realm dungeons and PvP battlegrounds, but players can only go in grouped with others already on their own server, then the rest of the party is selected at random from all Realms.