Apple announced that more than 600,000 pre-orders were placed yesterday for iPhone 4, while apologizing the problems many customers experienced trying to place orders:

Yesterday Apple and its carrier partners took pre-orders for more than 600,000 of Apple’s new iPhone 4. It was the largest number of pre-orders Apple has ever taken in a single day and was far higher than we anticipated, resulting in many order and approval system malfunctions. Many customers were turned away or abandoned the process in frustration. We apologize to everyone who encountered difficulties, and hope that they will try again or visit an Apple or carrier store once the iPhone 4 is in stock.

Suffice it to say if these numbers hold up, Apple might just have another hit on their hands.

[Apple PR</a]