Yafaray is a powerful yet free 3D photorealistic rendering software. It’s integration with Blender 2.5 and 2.6 is excellent. Together with Blender, Yafaray can produce stunning images. It is one of the few open source ray tracing renderers that sports global illumination and an comprehensive settings of features.
However, up-to-date documentation for it is sparse.
So far there is an ebook that is written for Blender 2.5 / 2.6 and Yafaray.
>>> Using Yafaray with Blender Book <<<
This book covers Yafaray as it is being interfaced with Blender 2.5 / 2.6 . In addition to that, there are also introduction to other relevant free software that can aid in the 3D process. The book also include additional examples.