Apple expects to sell 1 million to 1.4 million iPhones this weekend, this is excluding the 900,000 pre-orders. It has the possibilty to be the biggest selling product release in history!
http://online.wsj.com/article/SB10001424052748704629804575325661775151320.html?mod=WSJ_Tech_LEADTop
UPDATE: They sold 1.7 million. Apple's most successful product release in it's history.