Plagiarists, take note: Google will get you.
If anyone needs further proof of that, consider the case of Bryan LeBeau. In December 2003 Mr. LeBeau, a professor of history and dean of the College of Arts and Sciences at the University of Missouri at Kansas City, gave the university's commencement address. Mr. LeBeau spoke to graduates about the 'rich notion of citizenship' and a sense of history in which 'no culture and no civilization and no society has ever had a monopoly on wisdom or virtue.'
This would be perfectly fine except that those words also appeared in a commencement speech delivered a decade earlier by Cornel West, now a professor of religion and African-American studies at Princeton University and one of the country's best-known academics.
A cautionary tale. Many students, even very good Honors students, do not fully realize what plagiarism is and that it is wrong. Plagiarism is "a piece of writing that has been copied from someone else and is presented as being your own work." When in doubt you should always cite your source. It is better to be overzealous with your footnotes than be found to be plagiarizing. One Tulane faculty member, Dr. Janet Ruscher (and incidentally, winner of this year's Honors service award), has an excellent primer on plagiarism and how to properly cite material. The official material for the College of Liberal Arts and Sciences (incorporating Tulane and Newcomb Colleges) can be found here.
Note that different disciplines may have different methods of citation. If the faculty member does not provide you with a citation style or direct you to a handbook be sure to ask. But always cite your source, even if you are merely summarizing what they have said. Also, and more obscurely, if you use your own work from a prior class or paper and do not cite yourself, this too is plagiarism (and is, at the least "double dipping," trying to get credit twice for the same work). I once had a student who took several of my courses and 70% of a paper in his last class with me was from a paper he wrote for the first class. The topic was similar and, had he come to me, he could legitimately have used that material on the latter paper. But he did not discuss it with me and attempted to pass the older work off as new work. That is illegal.
Finally, Google will get you and so will Turnitin.com. Tulane has a contract with this service and many faculty upload papers to this site where they can be compared against a whole databank of other papers and the internet. I now have 4 years worth of student assignments that are (anonymously) stored there and available for comparison. So when in doubt, cite!
A nice concluding cartoon from the Chronicle of Higher Education by Carole Cable:
"You have very skillfully synthesized numerous themes within your sorority's freshman term-paper collection."