Windows Phone 7 won't support gyroscope functions in earlier devices, Microsoft's Brandon Watson said in a Channel9 interview. The OS may have it eventually, but not at launch, and Watson agrees it's a good idea. The issue was brought up by the inclusion of a gyroscope in iPhone 4, which will support it immediately.
During the interview, it was also revealed that the compass API will eventually be part of WP7, but again not at launch. Pivot and panoramic controls will be added to the developer tools before summer's end. Microsoft asked that any developers that use third-party tools to achieve the same goal switch to the official method once it becomes available if they want to make a more consistent experience.
A gyroscope is more precise that an accelerometer and performs largely the same function, but misses certain features. Users can't turn in place and have the phone recognize the position change. Google Maps and augmented reality apps on most Android and iPhone devices work by using a compass.