This is from the 2009 help menu. Click on the photo to see a closeup of the new Mental Ray Dialog Box within Revit.
Revit Architecture 2009 User's Guide > What's New in This Release > Rendering Enhancements >
What's Changed for Rendering?
|Revit 2008 Feature||In Revit 2009...||For more information|
|AccuRender radiosity and raytracing||Revit Architecture 2009 now performs these functions automatically when it renders an image. You no longer need to perform these functions as separate steps.|
|AccuRender environment settings, sun and sky settings||When you define render settings, you specify whether the sky is cloudy or hazy (or both), or a solid color. For the sun position, you can select from predefined settings, or define a sun position based on date/time/location or azimuth/altitude.||,|
|Render scenes||You define render settings for each view. To apply defined render settings to other views, create a view template. Then apply it to the desired 3D views.||,|
|AccuRender backface culling, view culling||Revit Architecture 2009 now performs these functions automatically when it renders an image. You no longer need to specify these settings.|
|External material libraries||Material definitions are stored as part of the project file. Render appearances are stored in a local, read-only library. If you make any changes to render appearances for materials, the changes are stored as part of the project. To share changes to render appearances with team members, use File menuTransfer Project Standards.||, ,|
|AccuRender procedural trees||ArchVision RPC trees|
|Seasonal settings||For many plants, you can now select a render appearance that shows a standard version of the plant or a fall version of the plant. You specify this in the plant family. The plant season is no longer a render setting.|