Perhaps no commercial vacancy in the last few years has prompted as much speculation on what should go there next as 57 South St., former home of Harvest Coop. Landlord Dean Rusk is marketing the property as a "retail/restaurant" opportunity, according to a poster in the window. Interested parties are asked to call 617-274-4900 or email firstname.lastname@example.org. Harvest shuttered the store in April, citing operating losses in each of the past three fiscal years. Harvest has a location .7 miles away across from Forest Hills Station.