Bryce does Object Masks and depth of field masks.

You can create masks, render particular objects with different materials and enviromental attributes and layer them together in Photoshop.
I've posted something similar here:

http://market.renderosity.com/mod/forumpro/showthread.php?thread_id=2659299

(check out Rochrs Cargo ship)

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Here are a few examples of MPR not in Bryce, but depending on how well you know your tools, you can achieve similar results.

http://www.rethinkfx.com/tutorials/compmax.htm

http://www.3drender.com/light/compositing/index.html

http://3dny.com/catalog/product_info.php?products_id=28

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Ockham's razor- It's that simple