Cook revealed the following in an interview with Charlie Rose last night.
It requires an iPhone, because they've been designed to work together. However, if you go for a run, and you don't want to carry your iPhone, music is also on your watch. So with a Bluetooth headset, you can run and listen to your music without your iPhone.
We'll let you know more about the Apple Watch as details become available. For now check out the announced features, specs, pricing, and availability here. Please follow iClarified on Twitter, Facebook, Google+, or RSS for more updates.