Apple COO Tim Cook explained Apple's iPod strategy at a Goldman Sachs conference yesterday: Sell less, make more. Worldwide iPod unit shipments were up 5 percent December-to-December — relatively low growth, thanks to slumping sales of Apple's cheap Shuffle. But iPod revenue still grew 17 percent. "Shuffle pulled the units down, the iPod Touch pulled the revenue up. Frankly, it was much more important for us to have a great launch on Touch and to establish that product ... than it was on units," he said. Cook continued: