I just try to reword the article in my own words when I have the time before I post the article since some web master are afraid of duplicate content making their rankings lower in Google, and don't want to be outranked in the search results from someone who copied and paste their article. I also put a link to the source.
Nope, I've not had this happen. But I have complained to another blog owner because they stole my articles. They even included the 'Enjoy, --Hissae2' part >_
I filed a Digital Millennium Copyright Act Complaint to Google at https://www.google.com/support/bin/request.py?contact_type=lr_dmca&product=adsense that some one was ripping off some of my blog articles without permission, but the site was one of those automated sites where the owner just use a bot to copy people's blog articles automatically, so I doubt he read my e-mail.