Johnathan Simon, from Official Google Webmaster Central Blog, indicated that you can now include different Content types in your sitemaps. So now you can include images and videos in one sitemap.

This is what the code looks like:

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"       xmlns="http://www.sitemaps.org/schemas/sitemap-image/1.1"       xmlns="http://www.sitemaps.org/schemas/sitemap-video/1.1">
<url>
<loc>http://www.example.com/foo.html</loc> 
<image:image>
<image:loc>http://example.com/image.jpg</image:loc>
</image:image>
<video:video> 
<video:content_loc>http://www.example.com/videoABC.flv</video:content_loc>    <video:title>Grilling tofu for summer</video:title> 
</video>
</url>
</urlset>

Johnathan Simon: "multiple content types in one Sitemap simplifies your Sitemap submission"