I have an interest in the curatorial and way-finding possibilities made possible by GPS and web enabled mobile devices. Over the winter I investigated attaching data produced in a CMS to a map by adding latitude and longitude fields to Drupal. I wrote a custom template to spit out data as KML so it could be consumed by a Google map embedded in a Drupal page. As a demontration, I made a couple Drupal articles linking to images of the Erie Canal and pinned those images to the map.
In April, Google announced changes to its API that made it less attractive to deploy for my clients. Today, I experimented with openstreetmap and openlayers. Google’s map service consumes KML and produces markers and handlers for generating popup info balloons when a marker is clicked. The openlayers library also easily consumes KML and automatically produces markers (good thing the Drupal instance spits out KML instead of writing directly to the Google Maps API). Openlayers does not automatically generate handlers for map events, instead, you must define them. While this is initially slower, it allows for much greater control and flexibility.
OpenLayers Screen Shot
Google Maps Screenshot