Plagiarism Detection Software, Its Use by Universities, and Student Attitudes to Cheating: A Report for the University of Sydney Teaching and Learning Committee
Tested Turnitin, EduTie, PlagiServe, Glatt Plagiarism Self-Detection program, CopyCatch Gold, EVE2 and WordCheck Keyword DP. Conclusions:

"There are a wide range of plagiarism detection tools and software available to universities and other academic institutions. Of these Turnitin.com appears to be the most widely used, and has been chosen by JISC in the UK for its centrally provided plagiarism detection service, and by CAVAL Collaborative Solutions as the program to market to all Australian universities.

Although plagiarism detection tools provide an excellent service in detecting matching text between documents, care needs to be taken in their use. A noted fault of the online services, such as Turnitin.com, is the inability to distinguish correctly cited text from plagiarised text, necessitating human intervention before a paper is declared plagiarised. This may pose a problem, or a barrier, to implementing such a service university-wide, especially in faculties where large class sizes are seen as a reason for not checking students’ work carefully for plagiarism.

The very fact that students are notified of the intent to use plagiarism detection tools to check assignments acts as a deterrent. However, information on the definition of plagiarism and how to avoid it should be made available to all students."