Well, not quite, but it’s nearly there and with a bit more work, maybe over the holidays, it’ll be perfect. Right now it takes selecting a photo in Aperture, opening an Automator.app workflow, edit the post title, running the workflow, and setting the correct category in the WP admin interface. Since I first took a screenshot of the workflow, I added a line to the shell script to delete the file after the upload was complete.
I found an Automator action called Post Text on Apple’s website, so the little shell script in the workflow is just about posting the right text, in the form of an HTML tag to display the photo in-line. Thanks to Jonas at Frozen Beetle Software for the Post Text action.