I don't agree that January would obviously be on the top. Consider that almost everything on the internet nowadays has the most recent piece of data on top: Twi

I don't agree that January would obviously be on the top. Consider that almost everything on the internet nowadays has the most recent piece of data on top: Twitter, Facebook, Email threads (anti-top-posting battle was lost years ago). As for Mandarin, yeah, that is true, but that is just one language among many. Some languages refer to past as "front" and future as "behind", should we make a 3d picker too? One reason they went with up/down may be to shelve the problem with right-to-left languages. But in that case they should use something more obvious. Note that a three letter abbreviation of a month is also not that much larger than an arrow...