Minecraft wiki entry for Development_versions, associated text: All Realms-related modules were moved into a separate library.
Future additional features to Realms will not require new releases of Minecraft.
New Features
Player activity monitor.
Access to more server settings.
PVP: On/Off.
Difficulty: Peaceful/Easy/Normal/Hard.
Spawn protection: Off/1..16.
Game Mode: Creative/Adventure/Survival.
Spawn Animals: On/Off.
Spawn Monsters: On/Off.
Spawn NPCs: On/Off.
Improvements in Realms UI.