Short definition: It's a more interesting and less pretentious version of the New Yorker
The Oxford American is a relatively small southern literary magazine. It premiered in 1992, and has published some of the best "southern fiction" to date, including an unpublished story by Walker Percy. The best issue of the year tends to be their July/August southern music issue. Two years ago, the cd that comes with the issue released REM's first song with out drummer Bill Berry. The magazine (who's tag line is "The Southern Magazine of Good Writing") is sponsored by publisher John Grisham and published out of Oxford, Mississippi.
On the web: http://www.oxfordamericanmag.com