You can get acceleration data that's well within the non-emergency situation from Macs. This thing works on Chrome on my Mac (which is a little disconcerting, to be honest):
http://www.html5rocks.com/en/tutorials/device/orientation/de...
And yes, the accelerometer exists to detect movement consistent with the shock of hitting the ground. For other purposes, the movement is way too small to trigger the mechanism.
A friend asked me WTF I was doing and it felt like a April fools joke.
Wouldn't be surprised if our Mac notebooks, being SSD based, didn't have the SMS
Edit: Apple says all Intel Mac notebooks have the SMS, but then goes on to say that SSD notebooks don't use them http://support.apple.com/en-us/HT1935
Yep, this is yet another vector to assist in de-anonymization of people - especially those using machines that often stay at a certain, specific x-y axis tilt on some desktops, etc.
I guess a knee-jerk, lizard brain fear response? Haha... Oh boy, I bet they'd really downvote me if I mentioned canvas fingerprinting. :P