As the reviewer says, "If you're running a WordPress blog, the OWA plugin is a must-have if you care how much traffic your site receives and where it comes from. I use it in combination with Google Analytics, and really like having both tools to see as much as possible about my site visitors."
Disclaimer: the developer of Open Web Analytics is my best friend, but that should not stop you from running OWA if you are running Wordpress. Not only that, the founder of OWA ran a data mining startup (Primary Knowledge) in a past life, so you're getting a real expert on data mining who's developed an open source analytics platform for wordpress.
You can also use it for tracking MediaWikis or any other web app that you care to integrate it with.
BTW, when are you going to start running Wordpress instead of Movable Type....so I dont have to write a perl plugin for you.