Here is a recent entry in my feed:
<item>
<title>Web Storage Sites</title>
<link>http://photomatt.net/2007/06/25/web-storage-sites/</link>
<comments>http://photomatt.net/2007/06/25/web-storage-sites/#comments</comments>
<pubDate>Mon, 25 Jun 2007 09:33:13 +0000</pubDate>
<dc:creator>Matt</dc:creator>
<category><![CDATA[]]></category>
<guid isPermaLink="false">http://photomatt.net/2007/06/25/web-storage-sites/</guid>
<description><![CDATA[Web storage sites loom as next big thing says CNET… in 1999.
]]></description>
<content:encoded><![CDATA[<p><a href="http://news.com.com/2100-1023-227606.html">Web storage sites loom as next big thing</a> says CNET… in 1999.</p>
]]></content:encoded>
<wfw:commentRss>http://photomatt.net/2007/06/25/web-storage-sites/feed/</wfw:commentRss>
</item>
On the regular site there are three tags and a category: http://photomatt.net/2007/06/25/web-storage-sites/
The same thing is happening in the Atom feed:
<category scheme="http://photomatt.net" term="" />
I suspect this is related to a term caching issue.