I just wanted to pass on the meme on a great RoR-based CMS - Radiant. It is OSS, very stable, fairly actively developed and has a really good plugin system.

While searching for a RoR-based CMS I looked at it a few others:
Mephisto

• Development has dried up due to the developers not having the time to continue it.
• No support for snippets (see below).

RailFrog

• Development seems to have dried up, the last messages on the blog were from 2006 and talked about a complete rewrite, which is usually a bad sign IMHO.

Some of the benefits that got me hooked on Radiant include:

• snippets (keep your content DRY),
• separate layouts vs content,
• layouts support custom mimetypes (ensure your RSS feeds get the right content type),
• the ability to structure the pages in a heirarchy,
• a set of custom tags for manipulating the content,
• built-in support for textile.
• Some existing plugins that make life evey easier, specifically Google Analytics and Virtual Domains (multiple sites from one install!).

The few limitations I see are:

• the plugin system needs to be improved to make extending the pages list easier,
• the blog-like functionality needs improving,
• some of the documentation needs work.

I've already used it on one site and am working to move all of our more static sites over to it - the less static ones will have to wait until I write a few plugins.