As an aside, I don't think gloating is something that I have ever experienced with real Christians (those who have given their life to Christ).
There is a fine line between being glad justice has been done AND taking pleasure from the suffering of another person (with the exception wherein such suffering leads to repentance).
I read God laughs: "The wicked plot against the righteous and gnash their teeth at them; but the Lord laughs at the wicked, for he knows their day is coming." Psalm 37:12-13 (NIV)