--- Operating System, Graphics card ---
Windows 7 x64, Geforce 540

--- Blender version with error, and version that worked ---
Error in SVN 57178, works in 2.67b.

--- Short description of error ---
If there is a Smooth Mesh with Edge split modifier, and afterwards an array modifier, the shading looks bad.
See attached blend file. Disable Array Modifier or move before the Edge Split modifier.

I suspect recent optimizations in the modifier stack, svn 57145. (Just a guess). ;)