Roomies, by Sara Zarr & Tara Altebrando

At the start of the summer after graduating from high school, Elizabeth receives a notice from Berkeley about her room arrangements for the fall, including contact information for her roommate.  Coming all the way from New Jersey, she figures it would be good to coordinate who's bringing what, so she reaches out to Lauren, who lives in San Francisco.  This starts up a correspondence that runs through the summer, full of plenty of adventures, anxieties, fall-outs, and reconciliations -- all without ever meeting in person.

It's not a book of surprises (girl meets girl, girl develops strong friendship with girl, girl hates girl after misunderstanding, girl makes up with girl -- plus the usual boyfriends, sex, younger siblings, and parents thrown in), but it is a charming read.  I would describe it as "Sisterhood of the Traveling Pants" without the sisterhood ... and without the pants.  The book is helped by the fact that Zarr and Altebrando are both decent writers and this team effort is good for showing their particular talents.  Presumably, they each took care of one of the characters, which allows for strong distinct personalities.  But being good team players, the characters interact well with each other.