I played around with all the different blogging agents available for Mac OSX, and found Ecto 2 to be the best of them all.
I have a Wordpress 1.5-based site, and this application has no problems interfacing with it, and it makes blogging so much nicer than trying to use Wordpress' built-in story writing capabilities.
The only drawback, is that it doesn't seem to handle Wordpress' page-creation capabilities, so it doesn't display (or allow you to edit) any pages created with Wordpress.
One other problem is that the included script 'Quote Safari' is broken. This isn't the fault of the script, but the fault of Safari. For some reason, there's a bug in Safari's applescript dictionary that prevents the Javascript portions of the code from working as anticipated. I've fixed the script and included it as an attachment on a story at my site: http://www.graffixjones.net/category/code-tidbits/, and there's also a how-to in the same story if you just want to edit the script that you already have.

This is a really handy little script, so it's a shame that it arrives broken.

Aside from the two problems I mentioned (no WP Pages support and the broken applescript), I'm really enjoying my blogging experience using Ecto 2. Let's hope than another update addresses these problems, but they really aren't 'show-stoppers'... just minor annoyances. One is easily fixable, and hopefully the other will be fixed in an update.