Something like the Elastic Plugin is another step in this direction. Although you probably need to know a little bit more than with the theme you presented in your post.

Here's the link to the Plugin:
http://wordpress.org/extend/plugins/elastic-theme-editor/

And here's the link to the presentation at WC NYC:
http://wordpress.tv/2009/11/14/daryl-koopersmith-elastic-nyc09/