Slashdot changed their RSS feed URL and never told me!
Sigh…
I just spent nearly two hours figuring out that Slashdot has changed the URL of their RSS feed. Their old RSS feed URL (http://slashdot.org/slashdot.rdf) generates a 301 “Moved Permanently” HTTP error. If you are using a browser, this will redirect you automatically to the redirect URL, which is http://rss.slashdot.org/Slashdot/slashdot/to.