epstopdf is a command line tool (available via fink) that does what it says: convert EPS to PDF files. If you give it an EPS file created from QuarkXPress or Adobe Illustrator, you might receive the error message "Warning: BoundingBox not found!". But if you look into the source code of your EPS file, there is a line containing proper "BoundingBox" information.
What's causing the problem? Older versions of epstopdf can only handle files with UNIX-, not Mac-style line breaks/line endings inside. To convert your EPS file to UNIX line endings, take a look at this hint and that hint. I currently use the free (but discontinued?) "BBEdit Lite" text editor for conversion.
As well, remove spaces from the name of the EPS file.
The epstopdf command from Gerben Wierda's TeX distribution is supposed to support Mac line breaks out of the box. If epstopdf --version yields something with gw, you have this variant.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20031205094042702