Well, I did this script for Maya. I first did it in MEL and then translate it to Python just as a basic exercise.
Basically this paints hard edges (like the corners of your objects), in a user defined threshold, using Vertex Paint.
Look for the Help in the script to get a lot more info about it.
Script based upon Neil Blevins' (http://www.neilblevins.com (http://www.neilblevins.com/cg_education/vertex_map_wear/vertex_map_wear.htm)): Worn Edges Using A Distorted Vertex Map and his DVD for The Gnomon Workshop.
Hope this will be useful. C&C welcome!!
UPDATE(18-12-2010): I got more feedback than I expected and worked on the script (I didn't expect any feedback to be honest, haha). There are a couple to do's pending.
UPDATE(19-12-2010): Added a new option that creates a Maya Set containing the vertices used by the script. This will allow you to do things like growing or shrinking the resulting vertex map using Maya's vertex painting and selection tools. Also, cleaned up the code a little bit.
UPDATE(20-12-2010): Uploaded the wrong version yesterday, sorry for that.