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Microsoft was hung, drawn, and quartered because under US law, it is not illegal to be a monopoly, but it IS illegal to leverage a monopoly position in one market in order to dominate a different market.
Many folks don't understand the law, and believe that a company is not allowed to have a monopoly position. That's not true; it only becomes a problem when the company seeks to exploit their monopoly status in different markets.
For example, Standard Oil used to ship so much of their oil by rail that they were able to dictate to the rail shipping companies how much they could charge for shipping competitors' products, and even for shipping cargo that had nothing to do with oil at all. Since Standard Oil was by far the rail shipper's biggest company, they were able to leverage their near-monopoly in oil into a near-monopoly into real shipping as well. (At one point, they were even making a tariff on oil shipped by other companies.)
Similarly, Internet Explorer's bundling with Windows was an attempt to extend a monopoly in one arena (desktop operating systems) into a monopoly in a different arena (Web browsing, and ultimately Web development, since people tend to code to the dominant browsers). That's why they got drawn and quartered.
If Apple had a monopoly on cell phones, and then tried to extend that monopoly into, say, game console development, by somehow using their cell phone monopoly to, I don't know, force Sony to rewrite their terms for PS3 development, then they'd be doing something similar.