So you want a rails application to give you a webdav? Good, railsdav can do this for you. However, it might take you an hour or two as well to figure out how it works :)
This plugin is a copy of the original railsdav plugin with some modifications to make it run out-of-the-box. Just drop this plugin into your newly created rails application and it becomes a webdav-server. It comes with Authentication, so you can publish and synchronize your ical-files without fear :)
This was done using Rails 2.3.2.
Get it here: http://github.com/funkensturm/railsdav