LHC
They have simply "scraped" your post and re-posted it. In This thread yesterday nitawriter discovered she was having a similar problem with posts being scraped and re-posted.
Essentially these sites are Spam Blogs or Splogs, designed specifically to make money - see how the google ads are wrapped around so many of the posts?
To be honest there's not a great deal we (yep I've had it too) can do to stop it. If it's on the net it's scrapable (is that a word??)
Bitacle was another such service that was successfully taken down. Have a read of the threads from that search for more information.
This first thing I would do is contact the blog admin and ask for your posts to be removed. Good luck with it, I don't think you'll get too far. You could also report them to Google for misuse of the adsense code (I think) and get them removed from the search engine for splogging and link farming.
HTH
Collin