Is nadolol (corgard) as effective as propranolol (inderal, innopran xl) in treating social anxiety?

NO. In theory, the answer is no because it doesn't cross the blood brain barrier as readily as propranolol. Nonetheless, it does block the catecholamine (adrenalin) response to stress/anxiety so it will still help and we all respond in our own unique way to every medicine so it may be excellent for some people.