Akuaku has compiled some code which will allow you to integrate Google Maps with any "Ruby on Rails" application. Here is the quick summary:
I've got some code here that should let you pretty easily add custom google maps to your rails app. It's far from complete but it's enough to get you going.
The following link contains the location to download the files required and instructions for setting it up in your Rails application directory.
If you're a Rails developer you'll know what all this is about. If not, here is the Ruby On Rails site which details what rails is and how it works. Basecamp is a good example of a rails app.