I used to have the same problem 2 months ago. It is not that easy to fight plagiarism and scraped content intruders... But there are ways!
Here is my path:
1. Check whether your content is unique and discover who might have stolen your content by visiting and checking our article(s) on http://copyscape.com
2. TAKE ACTION! Visit http://www.plagspotter.com
and check your content again! The site is like http://copyscape.com
but a free one + there is a lot of info about plagiarism
3. After you know who the thief is - contact him/her . Via his site. If there is NO response (which is to be expected) find his telephone number by visiting http://www.whois.com.
You will discover plagiarist's name, phone number, e-mail - all you need for the contact!
4. If there is no answer again - contact the hosting company and ask them to remove the plagiarist website or only your scraped/stolen content!
5. If there is no effect again - send a formal “Cease and Desist” letter and exercise your rights under the Digital Millennium Copyright Act (DMCA) and file a DMCA complaint directly to Google.
6. Visit this site - http://www.copyright.gov/help/faq/
- read all the info there + register (I think the cost is $35) and you are almost protected!
Do not forget to prove that the content is written by you! Visit http://archive.org/index.php
type your page/site and make a screenshot as a proof!
That is it! :-)