Linda Greenhouse says yes:

But during this past term, Justice Kennedy was in dissent in 5 of the 18 cases decided by five-vote majorities (a figure that amounts to one-quarter of the 73 cases decided with signed opinions, down from 31 percent in the previous term and 40 percent in the term before that.) Three justices to Justice Kennedy’s right, Antonin Scalia, Clarence Thomas and Samuel A. Alito Jr., all cast fewer dissenting votes in those close cases (three, three and four, respectively) and Chief Justice John G. Roberts Jr. was tied with Justice Kennedy at five.

Those are admittedly fine distinctions from a small sample, but I would argue that it’s the trend that counts. Justice Kennedy no longer appears to reside at the court’s center of gravity. The center has shifted to the right.

My buddy Mike Sacks at F1@1F has been making this point for some time.

Professor Cameron of the University of Indiana-Bloomington disagrees. His article, titled Have Chief Justice Roberts and Justice Alito Moved the Supreme Court to the Right?, suggests the Court is no more conservative now that it was with Rehnquist and O’Connor.

In 2005 and 2006, Chief Justice Roberts and Justice Alito joined the United States Supreme Court. At that time, many observers of the Court speculated that these appointments would cause the Supreme Court to behave in a more conservative manner. This remains the archetypal understanding of these justices’s impact upon the Court. However, a quantitative evaluation of the Court’s behavior both before and after Roberts and Alito joined the court demonstrates that, in fact, the Court is no more conservative with Roberts and Alito on the bench than it was with their predecessors, Chief Justice Rehnquist and Justice O’Connor.

I’m inclined to agree with Greenhouse and Sacks, especially in light of the October 2009 term where Roberts really has come into his own as the Chief, though I’m curious what empirical research this article relies on.