From the NYTs:
Judges around the world have long looked to the decisions of the United States Supreme Court for guidance, citing and often following them in hundreds of their own rulings since the Second World War.
But now American legal influence is waning. Even as a debate continues in the court over whether its decisions should ever cite foreign law, a diminishing number of foreign courts seem to pay attention to the writings of American justices.
“One of our great exports used to be constitutional law,” said Anne-Marie Slaughter, the dean of the Woodrow Wilson School of Public and International Affairs at Princeton. “We are losing one of the greatest bully pulpits we have ever had.”
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Justice Michael Kirby of the High Court of Australia said that his court no longer confines itself to considering English, Canadian and American law. “Now we will take information from the Supreme Court of India, or the Court of Appeal of New Zealand, or the Constitutional Court of South Africa,” he said in an interview published in 2001 in The Green Bag, a legal journal. “America” he added, “is in danger of becoming something of a legal backwater.”
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Turtle Talk 
Note: Sandra Day O’Connor thinks there is another factor that may influence why U.S. Supreme Court decisions are not followed. Australia may have established enough precedence to render its own opinions. ~ Sandra Day O’Connor, Question and Answer session with Lewis & Clark Law students on September 18, 2008.