Recently Github Pages stopped supporting Textile as one of the markup languages you can use to author your Jekyll site. They left Markdown as the only option, which makes sense considering that Markdown is widely supported and way more popular than Textile. This blog was originally created using Textpattern and Textile and that’s why I had a bunch of posts written in Textile that I had to convert.
The Github crew just published this post explaining the conversion process. The outcome is not perfect and you will need to review your converted files, but at the end it didn’t take more than an hour or two to convert all those old blog posts.