Sitemaps has truly been a basic SEO step for many large or even medium sized web sites. Google Image search has been a strong driver of traffic to many sites, but sometimes it is hard for webmasters to get their images indexed. Google announced support for images in Sitemaps.

Here is an example:

<?xml version="1.0" encoding="UTF-8"?><urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"xmlns:image="http://www.google.com/schemas/sitemap-image/1.1"><url><loc>http://example.com/sample.html</loc><image:image><image:loc>http://example.com/image.jpg</image:loc></image:image></url></urlset>

With this you can specify image, location, caption, geolocation, title and license. For more details, see this document.

Forum discussion at WebmasterWorld.