There's a nice scene where a depressed Heather hangs out with Zack in a garage. At first, he can't figure out why the little girl seems so sad, until he realizes that she's homesick. He completely drops his Jerkass Fašade and agrees to help her make a necklace to make her feel better.
And at the end of the movie, he's seen wearing the necklace! Aww.
At the end of the film, the four main kids have gotten past their issues and become a couple:
Zack drops his phony delinquent act and becomes a genuinely nice guy, who then hooks up with Trish, who has dropped her Ice Queen persona.
Mud gains confidence and the respect of his peers and hooks up with Gaby, who has gotten over her (probably parentally inspired) weight issues.