Apple's iPad is already huge. In fact, after just its first quarter of sales, it's already the company's third-biggest business segment.

In the June quarter, the iPad business generated $2.2 billion of revenue for Apple.

That's more than Apple's iPod business generated last quarter -- $1.5 billion. (Though the cheaper iPod obviously had larger unit sales.) And it's almost half as big as Apple's 26-year-old Mac business, which put in its best quarter ever at $4.4 billion.

Very impressive. And the fact that the iPad and Mac can apparently coexist is especially good news for Apple.

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