I'll soon have online my docs on getting Gld, a greylisting utility for Postfix, to compile and run under Mac OS X. It took a bit for me to get this working, but I'm learning as I go. ;)
Also, the author informs me that a new release of gld is in the works, and I hope to be running a beta of that shortly. The 1.0 release was pretty raw, the 1.2 version on the way should be a fair step forward.