Currently the DeviceMotion API is available on PlayBook and BB7 but not on BB6. It wasn't included in that OS version. However it is possible to add it to BB6 on the torch
Would really love to see this for some apps that I'm thinking about. I found that you had said something about it being in a zeta release (http://supportforums.blackberry.com/t5/BlackBerry-WebWorks/What-BlackBerry-WebWorks-API-s-are-you-looking-for/m-p/1089631/message-uid/1089631/highlight/true#U1089631), but cant find anything recent about this. Is there any road map for it now?