I have always allowed my kids to handle these things themselves. Being able to handle confrontation is lesson best learned early!
They have been able to talk about it in most cases but retaliation has been a solution on more than one occasion!
I am all for that, too.
However girls tend to be less assertive, and then our society shuns people who take care of their own business...you know, your kid gets attacked but still suspended because he fought back...
I think the parental input is still needed, especially at this early stage.
(I am waiting for an update tho...)