He made us revise, edit and re-write, honing our craft and skills even while driving us nuts. We can be scrupulous in citing our sources and being original in our posts. And we can refuse to tolerate thieves among us. Any instance of plagiarism should be reported to abuse. If it's a friend, by all means tell them what you found- it could be inadvertent or they may not know what they've done is prohibited.
Honest mistakes can happen.
This is one reason an e-mail contact address is important. Don't do it, and don't tolerate anyone that does. I know if they rated a piece discovered to be stolen. Be careful about jumping to conclusions or judgments. But using the Web Of Trust and reporting abuse is what Epinions asks of us to help maintain site integrity.