Android is number one OS among US phone buyers over the last six months
engadget.com
engadget.com
http://www.clickz.com/clickz/stats/1733041/apple-google-cont...
And if you follow stories about dirt cheap, but still impressively spec'ed low-end handsets like the Orange San Francisco (aka ZTE Blade) I don't think you'd find it unlikely that Android will rapidly overtake iOS here too.