Assuming I had markdown set as some default in Wordpress, I sent the post via MarsEdit to the server. After switching over to the site to check out my handiwork, I was, of course, not thrilled to find out that it had pasted a bunch of garbage and published it.
I copied the markdown from MarsEdit to my clipboard, went up to my Service menu and selected "Preview Selection in Marked" (part of the Marked Bonus Pack). This brought up Marked, displaying the formatted blogpost.
After selecting "Copy HTML", I just pasted the HTML back into MarsEdit and reposted to Wordpress.
BOOM. The entire operation took about 15 seconds. "Disaster" averted.
At $3.99, it's a steal if you use markdown at all. I use it every day, all day -- even though my tools-of-choice like nvALT and Byword have a markdown preview built into them.
Support for Scrivener will be a game changer for me, and actually see me using Scrivener a lot more for longform writing. I still have three or four long posts languishing in Scrivener because markdown has become such a key part of how I work and it was such a pain to preview those projects as easily as I can preview everything else.
Also worthy of note is that Brett has a very good design eye and his CSS skills shine in his new stylesheet, Upstanding Citizen. I preview a lot of my writing using that one because its so clear and easy to read.
Go buy Marked. Now.