Here's a bit of a mystery for you. I checked into one of my wikis today and found a new feature; green check mark with 'plagiarism checker' next to it. I navigated to the site, listened to the 60 second video and am impressed with the efforts of Brian Klug of the University of Maryland who is responsible for this great initiative. It's easy. Just copy/paste your student's text into the plagiarism checker's field box and it will determine if and how much of the work is plagiarized.
The mystery is that this 'feature' doesn't appear on any of my other wikis and the one on which I discovered it isn't even a premium wiki. I don't get it but I'm happy for the discovery. If you don't have this feature on your PBWorks wikis, you can get it at dustball.com. There is of course an upgrade version for a monthly fee.
As a parting thought, I really like the new navigational features on the PBWorks wikis. It makes moving from one workspace to another very simple.