Bleh for standardization, really.
It's better, in my opinion, to have a working prototype of a feature working and used by some early adopters than to build standards in a vacum.
Those early adopters need to know those features my disappear or the apis change and be ready to fix their code.
There is no need or sense in defending this behavior. It's bad, and shortsighted.
They all (ingeniously) use the sudden-drop detection that prevents hard drive head crashes to double as an accelerometer.
I assume it's really the other way around—a "sudden-drop detector" is nothing more than an accelerometer.
It's one of those things that are obvious in retrospect, but computers have had accelerometers used for sudden motion sensing for decades now, and most manufacturers employ this tech in some form or the other in their upper-end modules.
Yet it took one bright individual to figure out that there's no point in using the accelerometer just for SMS, when in fact, its API can be exposed to the world for whatever other accelerometer-related needs. I don't know why other manufacturers haven't followed suite, but given the state of the industry I would not be surprised if patents are, in one way or the other, to blame.
For the curious: http://en.wikipedia.org/wiki/Sudden_Motion_Sensor
Is this exclusive to Windows/OSX?
In theory, this is cross-platform.