I'm on the America's Test Kitchen mailing list - a recent email about maple syrup storage may be of interest:
According to the folks at
Cooks Illustrated, The syrup stored in the freezer never froze solid and, once warmed, was identical in taste to the refrigerated syrup.
Unopened, maple syrup will last several years stored in a cool, dark place. Once opened, it will keep six months to a year in the refrigerator.