Octopress is a framework designed by [Brandon Mathis](http://brandonmathis.com) for [Jekyll](http://github.com/mojombo/jekyll), the blog aware static site generator powering Github Pages.
To start blogging with with Jekyll, you have to write your own HTML templates, CSS, Javascripts and set up your configuration. But with Octopress
All of that is already taken care of. Simply [clone or fork Octopress](https://github.com/imathis/octopress), install dependencies and the theme, and you're set.
Short answer: Everything. Octopress is now based on [mojombo/jekyll](http://github.com/mojombo/jekyll) has been completely rewritten from the ground up with a mountain of goodies.
For now that's it. Check out the [docs](/docs), [kick the tires](http://github.com/imathis/octopress), post [issues](http://github.com/imathis/octopress/issues) send me [support requests](http://convore.com/octopress/support) and tell all your friends.