The site that you mentioned is probably a splog. Splogs have been around for ages. They take our freely available and easily accessible RSS feeds and use them to re-post our content with their tasteless ads.
First and foremost, you need to "claim" you feed by installing something like Better Feed. Better Feed allows you to create a custom footer for your feed that appears below every post. You can fill the custom footer with things like a copyright notice, a link back to your blog, and even a digital fingerprint to track content theft.
Next, install Bad Behavior to keep most content scraping bots from even visiting your blog.
After that it, it's up to you if you want to block bots either via user-agent or IP with your
.htaccess file. I strongly recommend against IP blocking as most spam bots and content scraping bots use dynamically generated or spoofed IPs, so you'll only wind up blocking an unsuspecting "victim".
AntiLeech still exists, and according to the creation date on the downloaded file, it was probably last updated 12/28/09, but whether or not it supports the latest versions of WordPress is unclear.
How do I find out who owns the site? What I actually want to do is see where it is hosted or where the domain name is ... and get them to take my article off their site.
This article provides tons of helpful tips.
They are using a wordpress blog On the bottom of the site it has a link to wordpress.org
Unfortunately, there's nothing we can do about that. They're free to use WordPress however they want to. Sometimes I wish there was some sort of magic "delete this blog" button we could push, but there isn't.