How can I get vertex painted .obj files to import into Blender? I have an .obj of a model that was polypainted (vertex painted) in ZBrush. I would like to import it into Blender and see the vertex painting in the 3D Viewport. Instructions for doing this in Blender Render and Cycles would be appreciated. 

I have already discovered how to export a .wrl file from ZBrush and import it into Blender following the following workflow:
-Export the model from ZBrush via Zplugin>3D Print Exporter>VRML.
-Enable “Import-Export: Web3D X3D/VRML2” plugin.
-Import the .wrl file, set Shading Mode to GLSL, enable Textured Solid and set the 3D Viewport to Solid shade mode.
This can also be accomplished with the ZBrush PLY import-export plugin.

I would like to know (if it is even possible) what the workflow is for doing this with an .obj file so that I can see the vertex colors like I can see them when opening the .obj in TopoGun or 3D-Coat. In either of those programs I don't have to set up materials or nodework (if it were possible) in order to make vertex painting visible and so that is what I am seeking here, just as it works with a .wrl file but using an obj.
june 2015:

Vertex Colors are not part of the .obj file type specification - see section on Geometric Vertex.

However some programs use an unofficial extended format for inter-change and add r,g,b information on the same line as the vertex coordinates.

# standard format (v: x y z)
v 1.0 1.2 0.3 

# extended format (v: x y z r g b)
v 1.0 1.2 0.3 0.5 0.2 0.2


Blender's .obj importer ignores everything after the x y z, therefore at this moment vertex colors are not parsed in any form.



If there was a color map (vertex colours) associated with the mesh, you'd  see it listed in 


menu: Properties -> tab: Data -> subheading: Vertex Colors


If there's nothing there then there's nothing to show.