Finally the countdown V-ray for Maya was over and now it launches, with the comprehensive list of features provided by V-Ray for Maya includes true 3D Motion Blur, Sun & Sky procedural lighting system, Physical camera for matching life footage, Environment Fog, a set of shaders and many others. V-Ray for Maya is an indispensable tool that is always there to help artists transform even the most ambitious creative visions into reality for both less time and lower cost without sacrificing quality.

Some featrues.

Image Sampling.

Full-scene anti-aliasing.
Support for additional render elements (diffuse, reflection, GI, etc).
Advanced color (tone) mapping controls.


Illumination.

Physically accurate full global illumination solutions.
Different GI algorithms: path tracing, irradiance cache, photon maps, light cache.
Physically accurate area lights.

Shaders.

Physically plausible materials.
Accurate hilights.
Blurry reflections/refractions.
Support for efficient material layering.

Camera Effects.
Supported Autodesk ^{Maya 2008, 2009, 2010.}
Multiplatform.

Read more in here: [link]

The lastest version of plugin RenderMan for Maya was availabled. The renderman for Maya 3.0 has a new compatibility with support to Maya 2009, 64bit Vista and Mac 10.5x Leopard. With this version, the plugin helps you easy to use with Maya and there are many new features:

Clean integration with Maya.
Software rendering of all Maya Particles.
Automatically render Maya Fur and Hair.
Render Maya Material networks, PaintFX, and much more!


Multithreading.
RenderMan's famous motion blur.
High quality displacements.
Fast and efficient fur and hair.
Fast HDRI and image based lighting effects.
Texture baking.
Advanced subsurface scattering.

And many features, you can read the full features in here: [link]

YafaRay is a open source raytracing render engine. As an open source project, users and developers have free access to the source code and it is free, as in free speech.
By using python scripts, YafaRay takes advantage of the new ID Property mechanism of Blender to retrieve most of the scene data, without adding any custom code to Blender. Other specific parameters are set up by a python-coded settings interface used from Blender.

Some features:

Point, spot, area, mesh, sphere, directional, sunlight, environment light (background)...

Multiple materials for a mesh.
Diffuse+glossy material (Ashikhmin&Shirley), Blinn or anisotropic microfacet distribution w. fresnel effect.
Emit material and basic glass (dielectric) material, with fresnel, filter, absorption and dispersion.
Multiple textures for a shader, UV coordinates, blending modes, stencil...
Perspective camera with raytraced DoF.
Transparent shadows.
Volume rendering.
Multithreaded rendering passes and radiance map creation.
Plugin based.
And many features... [link]

Official Website: [link]