Chris Boyd announced that the geotagging feature in WordPress for iPhone is now available for self-hosted WordPress sites, and can be downloaded at the WordPress.org plugin directory or through your WordPress dashboard: http://wordpress.org/extend/plugins/geolocation/
“The plugin adds a subtle but powerful addition to posts you’ve geotagged using WordPress for iPhone: a link appears inside your post with a short description of the location where the post was tagged. When your users hover over the link, an interactive map appears allowing them to view the location as a pin on the map.”
More info: http://iphone.wordpress.org/2010/05/03/geolocation-plugin-wordpress/