A lot of the work of analysis is triangulation. What pieces of imperfect data can you put together to point towards the right answer?
Flurry just gave a very nice set of triangulation points: figures for iOS and Android devices, both phone and tablets, that it's seen in China (i.e. using apps with Flurry's analytics software installed). The total is 260m.
This is pretty much consistent with the data I put together in a previous post here, suggesting well over 200m smartphone users.
So, the chart below shows how the Flurry numbers look in comparison with the US market. Again, the data is imperfect. The big US operators report unit activations and iPhone share of those, which allows us to compute an install base, and Comscore gives survey data, but the survey arrives at a slightly different number than that implied by the operators. And while Comscrore gives a specific Android number, the operators only give iPhone and smartphone activations. (Also, I don't have tablet numbers for the USA -or rather I do, but they come from yet another survey.)
Be that as it may, the sense of scale that this triangulation points to is pretty accurate. China probably has roughly as many iPhones as the USA and a lot more Androids.