For as much talk about Android -vs- iPhone, we're still not dealing with a real test of the various OS's popularity.
Bottom line: iOS is available on 1 device, on 1 carrier in the US. Android is on dozens of devices, on all the major carriers.
We will see a real test if (and only if) the iPhone is available on all 4 major US carriers. I am quite confident iOS will do well. Will android be larger? Quite possibly, but as a user of both operating systems (and reasonably tech savvy), I can declare unequivocally that I prefer iOS. Android, at this point, offers nowhere near the fit, finish, and end-user satisfaction of iOS. What android does offer, however, is flexibility in carrier and phone styles.
Don't get me wrong... Android has a great notification system, and the ability to use widgets (or not) is nice, but for other things like media playback / syncing, web surfing (pinch to zoom, scrolling, etc are so much smoother on iOS), and quality app availability, android is very far behind iOS.
If and when the iPhone is available on other carriers, we'll see where they stand... all of the numbers now simply reflect Verizon / Sprint / T-Mobile -vs- AT&T. How does Android do on AT&T... I don't know the answer to that, but I'd guess much worse than the iPhone.