What this tells us is that iOS has been getting most of the old BlackBerry customers. The shrinking of the "others" is hardly surprising. Symbian is now at less than 2% market share in the US and the rest is probably pretty evenly divided with Windows Mobile, Windows Phone and some even smaller OSs. Ironically, what this means is practice is that even in the US Symbian and Windows Phone are currently still pretty much tied, even if it's only because both have very small market share... The WP market share will probably get some kind of boost from Nokia 900, but how much remains to be seen.