GMap + Location Screencast
Drupal can store and display geographic information through the use of the contributed modules called GMap and Location, part of the geocoding module stack known as Mapadelic. Together they form the foundation of building rich maps using Google's map service.
This screencast covers the basic setup required to produce your first Google mapped nodes and display all your nodes on one big map.
Prior experience with Drupal 6 core will help you follow along with this lesson, especially in the area of enabling and configuring modules and customizing content types.