As part of the build out of a recent client site with location enabled architectural case studies, I modified the Gmap module (patching gmap_plugin_style_gmap.inc) to support taxonomy markers in Gmap Views (
http://drupal.org/node/327053). Previously custom markers were only displayed on the standard map/node page.
The inspiration for my patch was included as part of DEV (http://ftp.drupal.org/files/projects/gmap-6.x-1.x-dev.tar.gz) , but not the desired functionality.
