This is really handy to know:
If you are publishing to a blog system that does not recognize Markdown, and you can’t for example install a custom WordPress plugin to facilitate such recognition, you will need to see that your Markdown content is converted to HTML before publishing.
Starting in MarsEdit 3.6, a new per-blog option makes it easy to automatically convert Markdown content to HTML when you publish to a blog.
I’ve really got into the swing of writing in Markdown, and this allows me to use it even when writing for companies that don’t have it installed in their WordPress server.
As for my own WordPress installs (including the one that will host this blog, as soon as I have the spare time to do the move), and an install of Ghost: