I just released a Rails generator to create CSS Rounded Divs
The overview is on my blog:
http://joemcglynn.wordpress.com/2009/12/21/a-rails-plugin-to-generate-css-rounded-corners/
You can install the Rails Plugin from github: http://github.com/canonical/css_rounder
This is one of those UI things that will evolve as people use it and
give me feedback -- so let 'er rip
Joe