I'm slowly getting my blog world in order after the move from my own proprietary blogging platform to using Github + Jekyll hosted using Github Pages.
I've been using HTML pages for blog posts at API Evangelist, Kin Lane and other blogs, with 3 years of blog posts at API Evangelist and about 6 years at Kin Lane. There is a lot of legacy content to move from my EC2 driven blogs to Github.
Every time I would try and publish the posts as is, Github would reject my commit when it hit posts that didn't have compliant HTML, making it near impossible to publish everything. I was trying to clean up as much of it as I could, but it wasn't good enough. I needed a way to convert to markdown and clean house.
When I first started using Jekyll I wasn't really sold on markdown, in my mind I didn't mind hand rolling my HTML tags--I have been doing it for years. After Ben suggested I use markdown in my newly minted Github Jekyll projects I started to see the benefits. It is way easier to manage content that is being published as a blog, page or otherwise when it is markdown.
I am just finishing up converting all of API Evangelist and Kin Lane to use markdown, and will be using the Fuck Yeah Markdown API to convert blog posts from HTML generated in my blog editor to markdown before publishing to Github.