Scenario:
"I took a quick look around and couldn't figure a way to have an RSS feed for specific categories. Does anyone know of a way to make it happen?"
Solution:
Just specify the category number (catid) to the xml-rss2.php script, in the same manner that you would specify a blog number (blogid).
Example:
A url of http://www.example.com/xml-rss2.php?blogid=x&catid=y will show the RSS feed for category with id y from blog with id x.
Original forum thread (thanks, Frankenstein!):
http://forum.nucleuscms.org/viewtopic.php?t=11670