I really think the reason why people haven't done it is they're trying to compete on Apple's terms. Palm trying to out-iPhone the iPhone, Microsoft trying to o

I really think the reason why people haven't done it is they're trying to compete on Apple's terms. Palm trying to out-iPhone the iPhone, Microsoft trying to out-iPod the iPod, both of which weren't successful on the same level. You either need to transcend their technology (which is difficult given the positive brand experience that Apple has) or compete in different fields to truly beat them. This just hasn't happened yet.