The Freestyle Branch of Blender 2.5 has the Non Photo Realistic (NPR) renderer Freestyle built in. Freestyle allows you to render images in cartoon, brush-stroke, charcoal or any other style. The Freestyle integration blog offers regular updates on the state of development, and also some nice examples of the capabilities.
From the Freestyle integration blog:
Since the last blog update, the dev team worked on internal improvements concerning the interface between Blender 2.5 and Freestyle. The context issue reported in the last blog post was partially addressed, and now the branch is capable of .blend files having multiple scenes. Freestyle module parameters can be independently specified for each scene. The compositor should work with multiple Freestyle-based scenes as expected.
The remaining context issue is the question of how to provide style modules with a way of accessing the current scene being rendered. We have been contacting core Blender developers to discuss the most appropriate extension of the Freestyle Python API design.
The render of the week is a set of images offerred by Nakeyta Schulz. Precise models, approximate ambient occlusion (AAO) and strokes with Freestyle all together result in a very descriptive appearance. Node-based hatching and â€œfakeâ€ tone are also nice additions.