Has it? The iPhone is popular with geeks and rich folk, and mostly only in the US. Last I checked, such people weren't the majority of people. The iPhone has certainly pantsed WinMobile and Palm... but those were pretty easy targets to begin with. They haven't even come close to touching the global Symbian marketshare.
Who knows how accurate this is, but AdMob reports the iPhone as having a 50% share of the worldwide smartphone market. Moreover, even if they had a 1% share, I'd still say that Apple has utterly transformed that market. Any new versions of WinMo, Palm, Blackberry, Symbian, Android, etc will be influenced by and compared to the iPhone OS.
