Displaying images in atom feed
I had the same problem when trying to include images as enclosure, but it seemed that the easiest way for me was to include the image with the normal img tag to the html content.
(It's also wrapped in CDATA, which might affect the way Google Reader handles the content. I haven't tried without.)
The following example works for me to make atom feed images visible in Google Reader:
<content type="html">
<![CDATA[
<a href="http://test.lvh.me:3000/listings/341-test-pics?locale=en">
<img alt="test_pic" src="http://test.lvh.me:3000/system/images/20/medium/test_pic.jpg?1343246102" />
</a>
]]>
</content>