The following section talks about the XML Google Maps plugin.
The XML Google Maps plugin, version 1.12.1, by Patrick Matusz, allows easy sharing of custom maps in a variety of formats, including My Google Maps and Google Earth Plugin Maps. With this handy tool, you can also share a map of your geo-tagged Flickr photostream, Picasa Web Album Picture Map, or Next-Gen Gallery album, if your NextGEN Gallery Images are already Geocoded (EXIF). To Geocode your photos, use a free utility such as iTag, available here: http://itagsoftware.com/
The English language homepage for the plugin is: http://www.matusz.ch/blog/projekte/xml-google-maps-wordpress-plugin-en/
Before getting started, the first step is to create a My Google Map. You will need to sign up for a Google Maps API key here: http://code.google.com/apis/maps/signup.html
To add geo tags to your Flickr photos, log in to your Flickr account and click on Organize | Your Map.