I render a lot of Cars and other Meshes which are supplied by Clients originating from CAD Exports.
Very often I will have to go though a vast amount of faces and extrude them all by hand and check the normals.
It would be great if there was an attribute I could just add to these planes with a thickness value and direction for an extrude to be performed at rendertime.
Maybe you already know but I thought i might mention it anyway, but have you seen the thickness attribute in Maya 2012 (only added recently in 2012)? Add it to an object by again using the extrude but instead of extruding by local z which sucks, you could possibly try the thickness attribute.
Works a treat and is pretty much Maya’s answer to the shell modifier.
We’re using 2011 and I don’t see any plans to change this too soon. Good to know though.
Ah that’s a shame because I think it is exactly what you are after 
Hopefully your studio or accounts or whoever makes the call is able to get 2013 next year.