Justice David Souter is retiring from the Supreme Court at the end of this year's session in June. The ultimate pig in a poke, Souter was nominated by George Bush the Elder at the behest of his Chief of Staff John Sununu, in an effort to avoid a bruising confirmation fight. As a result, Bush's nomination turned out to be a reliable vote in the liberal wing of the court, and it squandered what could have been a more successful, judicially inactive Supreme Court.
Souter's departure does nothing to change the balance of the court. Expected departures of John Paul Stevens and Ruth Bader Ginsburg will also have little impact on court balance. President Obama may indeed get to make three Supreme Court nominations in his first term...generally speaking a boon to one's ideological backers...without making even a ripple in court make-up.
George W. Bush's wise decisions on Roberts and Alito will stand as among the most important legacies of his Presidency.
UPDATE: Just thinking about the delicious miasma of special interest horse trading that will go into this nomination makes me smile.....