A handy plugin to allow user control over the WWW redirects that often confuse and baffle visitors and search engines. I’ve not tested the plugin, but my guess is that it writes to your .htacess file, so anytime you experiment with such plugins, it’s always a good idea to do a backup of the file before the experiment. Hopefully Justin will clarify things if I’m wrong.
It actually doesn’t use the .htaccess at all. We didn’t want to deal with permissions/chmod at all so we went with PHP & some regex.