Commencement, J. Courtney Sullivan.
I felt like this book ended abruptly, but other than that, I have nothing but good to say about it. It reminded me a bit of Prep (Curtis Sittenfeld), except that it was set at Smith, an all-women college, and followed the four women more throughout their "adult lives" (when they graduated from college to the present, 4 years later) than their college lives, though it frequently referred to memories from them. It also sort of reminded me of Sisterhood of the Traveling Pants (Ann Brashares), in a weird way, maybe because there were four women (and in the Sisterhood, there are 4 girls).
Anyway, great book overall ... I highly recommend it. :)