PDF file created by ps2pdf -dEPSCrop comparefiles/ShadowText.eps foo.pdf looks different on Acrobat Reader (v. 8 or 5) from the source EPS file. Overprint Preview option has has no effect on the rendering. Ghostscript shows the same PDF file similar to the source EPS file.
Another issue with using FreeType, set -dDisableFAPI to true and the problem goes away. There are two other similar reports which are 'probably' the same issue, I believe these are all problems with type 3 fonts using type 1 fonts to generate special effects. They may all be Quark XPress files (this one certainly is), a noted offender in this area.
Fixed in revision 11617, patch here: http://ghostscript.com/pipermail/gs-cvs/2010-October/011845.html