The campaign tells Politico no:
One thing Obama did not do while with the review was publish any of his own work. Campaign spokesman Ben LaBolt said Obama didn't write any articles for the Review, though his two semesters at the helm did produce a wide range of edited case analyses and unsigned “notes” from Harvard students.
But Susan Estrich, herself a former Harvard Law Review editor, says the answer is almost certainly yes:
Estrich believes that Obama must have had something published that year, even if his campaign says otherwise. “They probably don’t want [to] have you [reporters] going back” to examine the Review.
For what it's worth, I've checked with some former Law Review colleagues who also believe Obama wrote an unsigned piece.