Make:

One of the more interesting recent news items is the announcement of Apricot, a new open source game development effort that is promising to produce a complete 3D game and development/production stack by the end of July 08.

The team will work on a cross platform game (at least Linux, Windows, OS X), using Blender for modeling and animation, Crystal Space as 3D engine and delivery platform, and Python for some magic scripting to glue things together. It is not only the purpose to make a compelling 3D game experience, but especially to improve and validate the open source 3D game creation pipeline, with industry-standard conditions.

I've only monkeyed with Crystal Space and Blender in the past, but I'm really impressed to see how far both of these applications have come and how they are now able to integrate with each other. There's a plugin for Blender called blender2crystal which makes it possible to develop maps and characters within the Blender 3D modeler, then export those models (including their physics and animation properties) into scriptable entities that can be used directly in the Crystal Space 3D engine. Tying the functionality of these two applications together is such a good move. Hopefully Apricot will help develop a solid model and some best practices for producing an entire game using these two tools.

If you can't wait until July to start digging through the Apricot code, there are several demos that have been made using Blender and Crystal Space that you should check out. The general outline is that you develop your game's 3D artwork within Blender, use Crystal Space as the underlying 3D engine, and then write your game logic in Python scripts which can control the underlying 3D engine via the CEL (Crystal Entity Layer) API.

Resources:
Project Apricot - Link
Crystal Space (3D Engine) - Link
Blender (3D Modeling Tool) - Link
CEL (Python Scripting for Crystal Space) - Link
blender2crystal - Link
Blender 3D: Noob to Pro WikiBook - Link