As everyone probably knows by now, the Senate has confirmed Elena Kagan as the next Associate Justice of the US Supreme Court. There was never really any doubt about the outcome. The fact that three dozen or so Senators voted against her confirmation can be chalked up to politics as usual; conservative interest groups, such as the National Rifle Association, were actively threatening Republican Senators who considered voting to confirm (see here).
Kagan has the smarts, the toughness, and the judicial temperament to be a worthy foil to the activist conservatives on the Court, including Chief Justice Roberts and Justices Alito, Scalia, and Thomas. Most importantly, she may prove able to sway the all-important swing vote of Justice Kennedy, at least in some close cases, with the quality of her arguments and her ability (displayed as Dean of Harvard Law School) to bridge divides. If she can do that, then her appointment to the bench is far more significant than simply replacing one liberal justice (Stevens) with another (Kagan).
Kagan's appointment gives the current Supreme Court a unique composition. For the first time in the nation's history, not a single Protestant justice sits on the Court, which is made up of six Catholics and three Jews. I'm not sure what difference this makes, but in contrast to mechanistic theories of judging so popular among Republican senators, according to which the personal backgrounds and prior commitments of judges does not affect outcomes, I am confident that it makes some difference.