DN, a national newspaper here in Sweden, have just launched their new site. They have managed to make quite a notable mistake, but one which is not uncommon. All of their existing RSS feeds have changed location. This in itself is not a mistake. Their mistake lies in not redirecting the old feed locations to the new ones. This would be a bad enough mistake for any URI, but RSS readers visit your site via your RSS feed – breaking the RSS feed cuts the link between your site and your reader.
The launch of DN’s website was announced to me via a “feed not responding” message in my news aggregator, Netvibes. I had to visit the site and manually find new feeds for all the old ones I had saved. Some people may not bother.
You need to take care of your readers, no matter how they come into contact with your content.