cnvi - 4:41 pm on Dec 31, 2010 (gmt 0)
This happened to us last year. It was scraper sites copying our blogs and articles to use as their own unique content. It didnt hurt our rankings but it didnt improve them either. Our rankings stayed where we expected them which was in the top 20 for most of our primary keywords. I would not worry about this. As long as you arent linking back to them you should be ok.