Minecraft version 1.3 will bring big changes to the PC version of the game. Single player Minecraft as we know it will no longer exist with after the update. Instead Mojang says the single player portion of Minecraft will be ” a shell on top of multiplayer”.
The changes are being made to help along the modding API which is still upcoming. “Minecraft 1.3 consists of a huge number of changes, and some of them are changes to the fundamental game engine. The most dramatic change is that we’ve kicked out single-player, and made it a shell on top of multi-player. There are two major benefits to this: first, it’s required for the modding api if we don’t want to have multiple implementations of every mod, and second, if we fix a bug in single-player, we know the bug is fixed in multi-player, too. Previously we had to fix bugs both in relation to single-player and multi-player,” so says Jens Bergensten on the Mojang Blog.
A list of the full gameplay features that will be pushed to Minecraft 1.3 can be found here. The majors include a trading system for villagers, and a handful of items like tripwires for creating mob-snaring traps.