Well, I kind of gave up waiting and hacked up something for my own forum, but the good news for everyone is that there is a free Zip Code database here: http://sourceforge.net/projects/zips/
My own code isn't of much use here because it's a Buddy program for a VB
forum, but the database itself is great, and the source code for a distance feature is included so you can test it out yourself.
The database included in the .tar gets extracted by the install program and creates a 5 Meg mySQL database of zip codes and geographic data. It's based on the 2000 census, which is public domain and free (well we probably paid through the nose for it with our tax dollars).
So you can save the $39 to spend on the next photopost product. Maybe Auctions?? PLEASE!