Minecraft Realms is a subscription-based server hosting service, which is currently in production for Minecraft: Pocket Edition and Minecraft: Windows 10 Edition Beta and developed by Mojang.
Cross-platform play between every available platform (iOS, Windows Phone, Android and Windows 10) will be of course supported in Minecraft Realms, but people will have to create an Xbox Live account in order to login.
You will only need a free account, no Xbox Live Gold membership is required for this service, so that’s an easy move for everyone who wants to use Minecraft Realms. According to Mojang, an Xbox Live account will only be required for online play, and not for single-player Pocket Edition.
A free alpha is currently running for Minecraft: Pocket Edition players using Android devices.
A pricing plan for Minecraft Realms on Minecraft: Pocket Edition and Minecraft: Windows 10 Edition Beta has not been announced yet.