No gyroscope in Windows Phone 7, at least initially
Recently at TechEd 10, Brandon Watson and Peter Torr discussed Windows Phone 7 development on Channel 9. You can watch the whole thing here, though suffice to say it's not the most exciting video nor does it shed too much more new info.
However, it was noted by Mobility Digest that there won't be any Gyroscope support for WP7, at least not right now. The new iPhone 4 has an electronic gyroscope which is supposed to be more sensitive than just an accelerometer. When combined, it should give the phone a more stable and accurate portrayal of its location in three dimensions. Why would that be important? For the growing area of "augmented reality" programs. Sure the accelerometer will help there too, but the gyroscope is even better.
In Microsoft's defense, we can see this as not being a top priority, so we'll allow this one to slide for future updates.