New twist on gravitational spin?

One of the last predictions of Einstein's general relativity not yet confirmed by observation or experiment may have yielded to careful measurement. Einstein predictcd that the spin of the Earth should create a gravitational field that affects other rotating objects. This field should, among other things, cause gyroscopes to precess. NASA is planning to launch the Gravity Probe-B mission in 1999 to measure this precession and hence verify Einstein's prediction