One of the new API’s supported in Microsoft’s Motion SDK is gyroscopes, a technology not present in the current Windows Phone 7 Chassis 1 specification.
In the developer Q&A after today’s MIX 11 keynote Microsoft has made it clear that the current crop of Windows Phones do not have hidden gyroscopes, and that this feature will be reserved for new devices coming in the fall.
It is not known what other features these new devices will have, but the most obvious unannounced element is front-facing cameras, now almost standard on high-end Android and iOS devices.