A fun fact from The Wall Street Journal just in time for Apple earnings:

Cash comes in before it goes out in part because Apple has incredible negotiating leverage vis-à-vis its suppliers. On average, in fiscal 2011 it didn’t pay suppliers for 83 days after being invoiced, according to Sanford C. Bernstein analyst Toni Sacconaghi. Yet Apple collected on its customer invoices much faster, 18 days on average. Meanwhile, it paid to keep just four days of inventory on hand in 2011, versus an already impressive 10 days in 2010.

While the scenario above oversimplifies (it takes many months to set up device assembly lines including testing and fault tolerance for instance), capital investments in manufacturing are heading toward null game for Apple.