I've been using something very similar for my blog for the past month or so, it's called Toto. Flat file, git, Ruby, Markdown, Disqus, etc. Check it out: http://cloudhead.io/toto and a good post on how to get up and running http://fadeyev.net/2010/05/10/getting-started-with-toto/ . It was really fast and simple to go from 0 to blogging. The default template is nice too (jlank.com)