think of good_book.doc and x students al writing their 'own' report about it. Now all a teacher has to do is a batch compare and report all same reports.
Example:
Student 1 - book report 1.doc
Student 2 - book report 2.doc
Student n - book report n.doc
Now compare and find all 'copy and past' actions done by the students and print a log report.
Compare It! can not do that. I already have plans for something similar in future, as additional application. But I think I have heard about such tool for teachers in Internet.