If you’re looking for a CMS built in Ruby on Rails, here’s 3 solutions you might enjoy (in no particular order):
Adva-cms is an open source cms plattform based on Ruby on Rails and Rails Engines.
Radiant is a no-fluff, open source content management system designed for small teams.
Browser CMS is a new-comer on the Rails community but promise to stir things up. Take a look at their video presentation.
And here’s 3 screenshots of each CMS in action: