I have used Google Reader to mash two image rss feeds together for Hubble.
Here is the HTML page for it:
https://www.google.com/reader/shared/user%2F15478232717259537591%2Flabel%2FHubble
Here is the RSS Feed:
http://www.google.com/reader/public/atom/user%2F15478232717259537591%2Flabel%2FHubble
Based off of:
http://hubblesite.org/newscenter/newscenter_rss.php
and
http://www.spacetelescope.org/rss/feed.xml
Enjoy space nerds.