This video presents a fairly compelling case that Apple will be getting into the Ringtone business with the release of the iPhone. Ringtone sales are big business, accounting for 10% of so of the global music market, and well over $1 billion per year in sales (see this old study for 2003-2004 industry numbers).
This news comes as others are talking about the price of the iPhone, which studies are saying is too high for consumers to stomach. My instincts tell me the studies are meaningless, though, and that Apple will sell these things as fast as they can produce them in Taiwan.