Apple's Cash Cow: iPhone

As observers continue to ooh and ahh over Apple's new iPad tablet computer/e-reader/overgrown iPod, analysts are marveling at the company's swift revenue growth due the iPhone. Launched in the summer of 2007, the iPhone accounted for a little more than 1/3 of Apple's revenue in Q4 2009. $5.6 billion of Apple's $15.7 billion in revenue came from the iPhone (and iPod Touch). The market should soon tell us if the new Apple iPad will be as big a game changer as the iPhone was (and the iPod before it).