I personally think that is a good idea. Gives people time to get something for you that you may want. I am pretty sure that Miss Manners would say No! It is a clear indication that you are expecting a gift, something that is rude to begin with. And then to provide a shopping list just takes it another step. Registering your preferences for things like silver and china patterns is one thing, but providing a list of goods with the invitation is another. If someone asks, you can tell them where you are registered.