What has always amazed me about relativity is the number of predictions Einstein's theories led him to that he had no way to test, but have since been demonstrated. Many of the consequences of relativity are so small that they are hard to measure (if they weren't we'd notice them in everyday life), but they have large consequences in the evolution of the universe and certain things that are still happening today.

Close to a century after Einstein introduced his theories, scientists have demonstrated another predicted consequence. Basically, relativeity says that gravity works by heavy objects distorting space-time. One consequence of this - a consequence thatr has now been demonstrated - is that rotations will further distort space-time through something known as frame-dragging. One discription was to think of it as twisting a spoon in a viscous material such as honey, the honey gets distorted neat the spoon, but doesn't move further out.

The research used 3 satellites. The positions of 2 were monitored by bouncing lasers off of them - the goal was to measure deviations from a perfect orbit. A third was used to map the Earth's gravity field so that the data could be corrected for that (because the Earth is irregular (different densities, uneven surface), the gravity feild is also irregular).

The end result? A 99% agreement with Einstein's theory, well within the experimental error.

NASA has a satellite with a slightly different technique for measuring the deviations (based on monitoring deviations relative to a star), which should prove more accurate, but the study is not yet complete.