Google Scholar - in beta since 2004 - epitomizes the problems of the internet. It provides easy access to advanced research that can be used by students - but whether it is used for citations or to plagiarize is the deeper problem.
The site uses an academic approach to ranking. "Google Scholar aims to sort articles the way researchers do, weighing the full text of each article, the author, the publication in which the article appears, and how often the piece has been cited in other scholarly literature. The most relevant results will always appear on the first page."
What plagiarists must know is that professors know how to use it as well to check if they are cheating. There are even sites like turnitin.com where teachers can submit papers and have them checked for originality.
Without a doubt Google Scholar helps improve access to academic research for students, and students are becoming well aware that teachers are tech savvy as well. If used properly it is a great example of the benefits the web provides.
Google Scholar has even released a toolbar plug in for Firefox browsers.