I can't imagine tilapia being that good on the grill -- not flavor-wise (isn't everything cooked over coals better?) but the filets I get are quite thin and delicate, I can't imagine them not falling apart unless you had a special basket or put them in foil first.
On the other hand, I have made fish tacos with them and they did quite well. yes, they do fall apart, but who cares? I usually saute a thin sliced onion, garlic clove in olive oil. Meanwhile slice the tilapia filets. Toss them in and saute quickly (stir-fry sort of method) with cumin and pepper of your choice. Watch it, they cook quickly. Finely shredded cabbage, and in addition to your favorite salsa a sour-cream type sauce (ranch works). Yumm.
My favorite is to bread them, then quickly saute in olive oill. Deglaze the pan with dry vermouth, a squeeze of lemon, and some capers.