The xVector Engine is a cross-platform 2D MMORPG engine written in Python. It will be a full-featured MMORPG engine allowing rapid game development without any programming knowledge, while still being easily extended with a Python scripting API.
Zen Worlds is an object oriented C++ virtual worlds / MMO game engine framework. This project includes Zen Engine game engine client, Zen Enterprise, an Enterprise Service Bus, and a C++ Application Server, and Zen Studio, a game development IDE.