ruby script/plugin install http://svn.devjavu.com/sitemapgenerator/

example:

script/generate sitemap photos daily

will generate a photos/sitemap.rxml template which renders a sitemap amongst other things. Be sure to check out the generated controllers since they hold the routes you need to add to config/routes.rb

Strictly speaking a RESTful controller is not necessary as long as the controller name is pluralized etc. You're better of going with the REST.

There is currently no advanced documentation for this plugin.