http://gmaps-samples.googlecode.com/svn/trunk/spreadsheetsmapwizard/makecustommap.htm
Embed a dynamic map of a public Google Spreadsheet on your webpage. After loading in your spreadsheet data and customizing the map, you can copy the generated code into your webpage. An example spreadsheet's data and map of great Seattle restaurants has been pre-loaded. You can view the original spreadsheet in HTML or XML. This wizard uses the Google Maps API and Google Spreadsheets API.