Instead of traditional server merges, players in Azeroth are experiencing server connections to aid low population realms. These connected "World of Warcraft" servers function together, share grouping and guild options, and even share an auction house. A plethora of new realms are being connected together tomorrow, Nov. 4.
The following realms will be connected during the maintenance on Monday. This maintenance is planned to occur at 6 a.m. PST and end at 11 a.m. PST.
Haomarush and Detheroc/Dethecus/Blackwing Lair
Stonemaul and Bloodscalp/Maiev/Boulderfist/Dunemaul
Daggerspine and Aegwynn/Hakkar
Tortheldrin and Frostmane
Dentarg and Whisperwind
More connections are planned according to the list, but these connections have no firm date attached to them. Realms that are connected use the game's cross-realm technology to permanently link servers together. The game world, of course, becomes more populated because of the connection making some things a little more time consuming. However, the world should seem more alive with more players in it. One of the notable benefits from connecting realms rather than merging them is that players will not be forced to choose new names if another player from a connected realm has the same one.
For more information on realm connections, check out the official post on the matter.