I just realized that TextMate includes a bundled command to preview Markdown-formatted text. Since I'm using the Markdown option for formatting in Typo, that means I can use TextMate as my blogging tool. I just save a file named post.markdown
to get TextMate to notice that it's in Markdown format. Then the key combo CMD-CTRL-OPT-P generates a preview of the formatted output. Copy and paste into Typo's article creation form and I'm done!
So cool!
You might want to checkout the new Blogging bundle, which features XML-RPC client support (written in Ruby!) for direct posting to most popular blog engines.
Allan mentioned a screencast demonstrating its usage soon.