Forgiveness is definetely a virtue. At my age, and with all the high school type situations, most of the things that people are doing won't matter in the long run. I'm pretty good about seeing the big picture, which makes it easy to forgive. I agree with Kon-Tiki, if somebody has done something bad, or wronged somebody, but they are proud of it, then it's not ok to forgive.
I do believe though, that even if someone is proud of what they have done, that you should still show mercy. Meaning, if they realize that they have wronged somebody, and they begin to feel guilty for it, you should still show them mercy and forgive them.
That's all