I think work done with the node editor and procedural textures in Blender cannot be exported via fbx.
The answer may be to use substance materials. Unity 3D is about to support them.
Take a look at:
http://forum.unity3d.com/threads/86414-Substance-answers-!?highlight=substance+designer
Is it possible for Blender to incorporate substance materials?
The Substance technology is proprietary and thus likely has an incompatible license (when it comes to incorporating Substance viewer code into Blender)
However there’s an Open Source equivalent where it would be legal for Blender to directly read and render the procedural format (though they could use more developers)
http://neotextureedit.sourceforge.net/
Thanks. I did not know about NeoTextureEdit. I will take a look at it.