Today we can announce that the four main developers of bukkit - a community-based Minecraft server implementation - have joined ranks with Mojang to bring you the same flexibility and versatility to the official Minecraft server. The four, Warren Loo (@evilseph), Erik Broes (@_grum), Nathan Adams (@dinnerbone) and Nathan Gilbert (@tahgtahv), will work on improving both the server and the client to offer better official support for larger servers and server modifications.
The plan is to build a fresh server API, and then extend it to support client-side modding (in one way or another). We will try to make it easy for bukkit users to convert if they wish to do so, but backwards compatibility is not guaranteed. We will, however, help bukkit to be compatible with 1.2, to avoid having a long gap while you wait for the official Minecraft server to catch up.
Many of you may ask why we decided to work with bukkit instead of other Minecraft teams, such as Spout or Forge. The reason is that we want more than just modding, and these guys have always had server admins in mind when developing their additions to the game. We hope that this will help the quality of Minecraft multi-player to improve, both for large and private family servers, while still being able to add fun stuff for the bigger audience.
In addition to the bukkit members, Daniel Kaplan (@kappische) will join to handle the project lead to coordinate Minecraft's broader goals. I (@jeb_) will remain as lead developer and game designer for Minecraft.