IMHO, it is - you have more glycogen built up from eating all day. Since the fat-burning from weightlifting happens AFTER you lift, not during (for the most part), it makes sense to take advantage of as much energy as possible to do the muscle-damaging work that is weightlifting, and then rest and sleep while your body heals the damage and grows new muscle (the metabolism-boosting part).

However, this advantage is NOT enormous. If you simply CANNOT do your weights at night, do 'em when you CAN.