I'm not at all an Instagram user. Since I am much more language-driven than image-driven, it's just not something I've used. But I came across this article about the really weird response of iPhone Instagram users to the reality that they released an Android version.
As an Android user, I've often thought of the Android/iPhone divide as one that was more about open vs. closed, and choice. Android is a sort-of open source mobile operating system, there are many fewer restrictions as to the ways app developers can develop on the platform, and there is a vibrant hacker community that Google doesn't bother to police (in fact, the cyanogenmod codebase is hosted on google code!) Apple has been trying to say that jailbreaking your phone is illegal (but the court begs to differ.)
And, of course, there are tens of phones with a wide variety of features to choose from that run Android, and only one iPhone.
It appears, based on the vocal outcry on twitter (well, I don't know how scientific a sample that is) that iPhone users think of the Android/iPhone divide as a class divide (and, in some cases, a race divide.) I wonder how widespread this perception is. It's also, frankly ludicrous, since the majority of newly-released Android phones cost as much as iPhones - out of the reach of a lot of people in this country (let alone the world,) and you can get both older iPhone models, and low-end Android models for free from some carriers.