USA Today reports on the use of software to identify plagiarism in universities:

Digital plagiarizing calls for digital policing.

Such is the philosophy behind a wave of anti-plagiarism digital software that colleges are using to deal with the widespread use of essay-writing websites and online databases of pre-written papers, and to uncover writing copied from other students' work.

Makers of programs called TurnItIn and MyDropBox.com have extended their reach through contracts with universities, and in some cases with textbook companies that include the software with the book so students can check their work for proper sourcing before turning it in.

The reach of TurnItIn grew from 6.84 million students to 9 million between 2005 and 2006. For MyDropBox.com, the numbers have climbed steadily from 700,000 students in 2005 to 1.4 million in 2006. Annual licensing fees range from 40 to 80 cents per student, depending on the number of students in an institution.

Logiically, it would seem that the same techniques could be used to protect copyright. But perhaps the universities have less interest in this problem.