Is gelatin vegetarian?
Without further qualification, if someone refers to themselves as vegetarian (in America), the general assumption is that they are lacto-ovo vegetarian. That means they don't eat animal products that require killing the animal, but eggs and dairy are fine. Gelatin comes from a dead animal (unless they start harvesting it with arthroscopic probes :), so it is not a vegetarian ingredient. There are many other hydrocolloids, such as agar, that can be used to produce similar textures if needed.