Greetings, This message is for the Google XML Sitmap plugin author. I worked on a client project over this past week where I discovered some nice hook via your plugin to add in non-WP URLs. Very nice!
I'm also the author of the Media Tags plugin http://wordpress.org/extend/plugins/media-tags/
I was reviewing your build interface and thought I would suggest adding a hook to allow other plugin authors the ability to add to your interface. For example under the 'Sitemap Content' section it would be nice to allow insertion of a checkbox so users can select to include the media-tags from my plugin. I would of course manage the insertion of the media tag pages but thought it would be better to add the control to your interface instead of building that into my own interface. Sort of keep things together.
Just a thought. Love your plugin. Thanks.