Some companies do put gelatin and/or mono & diglycerides in ice cream. If you are vegan, those incredients would be a no-no, but most lacto-ovos only avoid visible pieces of meat, meat stock, etc. Eating dairy ice cream with gelatin in it does not make you a nonvegetarian. Feel free to avoid whatever ingredients you want, though, as your conscience dictates.
Q: How many poets does it take to change a light bulb? A: 1001...one to change the bulb, 1000 to say it's already been done.