The Ileor Framework v0.02 has been released recently at the project website. Ileor is a plugin based, distributed framework for quickly deploying massively multiplayer online games. It can also be used to rapidly introduce multiplayer features into existing games.
The core of the framework consists of a client and server that handle all the networking and plugin management. All extra functionality can be programmed as plugins which can be loaded as dynamic libraries or made to use sockets to communicate with the core (or other plugins). The plugins can be written in C++.
We hope to have community contributed plugins for people to download and use for building their own MMOG's. Currently the project is written only for Linux, but can be made to run in a multiplatform environment with a little tweaking (will be available in the near future too).
You can get your hands on the project at the the project website!