WordPress Category Feeds!
Locating the URL for your category feeds is not always the easiest thing to do with WordPress. TangognaT points out that it’s as simple as adding a ?cat=# of category to the base url for any wordpress feed. So if you wanted to display the RSS feed for category 3, the feed URL would be http://www.yourwebsiteurl.com/wp-rss2.php?cat=3. You can also use wp-atom.php?cat=3.