Jason Gilmore has written an excellent article for those of you tackling the Google Maps API and creating all of these great mashups. It's a primer for making the most of the GMaps API...
Integrating Google Maps into Your Web Applications
By Jason Gilmore
Perhaps the most famous applications embracing the Ajax model is Google Maps. Surely you've played around with this website, perhaps entering your or other addresses of interest, and marveled as how the site responded to zooming and dragging around on the map in seeming real-time. Wouldn't it be great to incorporate Google's mapping capabilities into your applications, taking advantage of not only its enormous database, but also the eminently cool interface that comes with it? (read the entire article..)