First of all it might be helpful to describe what gluten is, what challenges it may or may not cause, and where one might find gluten in the grocery store, pantry, or refrigerator.
From the informative article linked below:
"Gluten is the protein part of wheat, rye, barley, and other related grains. Some people cannot tolerate gluten when it comes in contact with the small intestine. This condition is known as celiac disease (sometimes called non-tropical sprue or gluten sensitive enteropathy)."
"Celiac Disease is the most common, undiagnosed, serious intestinal disease in the United States."
"In patients with celiac disease, gluten injures the lining of the small intestine. This injury results in weight loss, bloating, diarrhea, gas, abdominal cramps, or vitamin and mineral deficiencies. When patients totally eliminate gluten from the diet, the lining of the intestine has a chance to heal."
"Removing gluten from the diet is not easy. Grains are used in the preparation of many foods. It is often hard to tell by a food's name what may be in it, so it is easy to eat gluten without even knowing it. However, staying on a strict, gluten-free diet can dramatically improve the patient's condition. Since it is necessary to remain on the gluten-free diet throughout life, it will be helpful to review it with a registered dietitian."
The trouble with removing gluten from the diets of celiac sufferers (perhaps up to 1% of the US population), is that this protein is widely used in food manufacturing processes, primarily to add protein to an otherwise low-protein food.
The main challenge I find as a baker, is that gluten is what drives the bread baking process; providing the structure, texture, and rise. Providing a gluten-free baked product that tastes, looks, and acts like bread is a challenge.