I'm in the middle of Sixteen, which is edited by Megan McCafferty, who wrote all the Jessica Darling books (Sloppy Firsts, etc.)
It's so cool!

I haven't read everything, but here are some bits I loved:

"The Alumni Interview" by David Levithan, in which a gay teenager has to face his boyfriend's homophobic father in his college admissions interview.

"Mona Lisa, Jesus, Chad, and Me" by Carolyn Mackler, which is about the end of a friendship -- something that I tried to write about in The Boyfriend List as well.

"The Perfect Kiss" by Sarah Mlynowski, who mainly writes for grown-ups but whose first teen book, Bras & Broomsticks, is coming out next spring. In it, a girl gets dumped by her boyfriend and contracts mono, spending the worst sixteenth birthday ever. But she gets revenge.