Another way to do it that works great for me:
Put the bottles in the dishwasher. If you have it use the extra hot setting. Don't use soap obviously. You can also do it in the rinse only cycle to save time if you washer will dry after "rinse only". Then when the bottles have been rinsed, about halfway through the drying cycle, open up the dishwasher and they should peel right off. The soaking with water, combined with the steamy environment of the drying cycle gets them so loose some may just fall off on their own! Make sure to check the bottom of the dishwasher for loose labels. I have had great success with this method. Just don't forget to pull them out before the drying cycle dries them or you have to start all over.