Fundamentally, plagiarism is about passing someone else's work off as your own. Note that this is possible even if you cite that work.
Plagiarism In 1918 http://mikecanex.wordpress.com/2012/05/06/plagiarism-in-1918...
Looks awfully similar to Plagiarism in 2012.
Wonder if an average theft or rapist should be walking around with recent statistics of population being behind bars and why it should be ok to steal or rape.
http://web.mit.edu/academicintegrity/citing/whatandwhy.html
(To be honest, I got this link from wikipedia :)