HelixBlog is a simple Ruby on Rails weblog application that helps you focus on writing above all else; it has all the features you want in a weblogging applicaton wrapped in an efficiently designed interface that eliminates clutter. By focusing on simplicity and usability, HelixBlog allows you to spend your time writing, rather than managing a convoluted CMS.
You can checkout the latest 'bleeding-edge' HelixBlog code. Be advised though, that even if I try to keep the SVN code as clean as bug-free as possible, the code might have minor incompatibilities or issues. Use it at your own risk.
svn checkout http://v.userdot.net/helixblog/trunk helixblog
Or you can view the SVN sources at:
http://v.userdot.net/helixblog/