Ever since Supreme Court Justice Sandra Day O'Connor announced her retirement there has been much speculation on who the next justice would be, and even more pontificating on who the nominee should be. Much of this speculation has been based solely on some rather ridiculous ideas that have no place in our political system, or any rational political system for that matter.
For instance, there has been much insistence that the nominee should be a woman, because a woman has retired. Why? Had that principle, the principle of discriminating based on sex as opposed to merit, been in place when O'Connor was appointed, she would have been passed over for a man. Discrimination against men for being men is no better than discrimination against women for being women (although there are economic reasons to discriminate against some women in environments of forced maternity leave, forced healthcare coverage by employers, etc.)
Another absurdity being bandied about is this notion of ideological balance on the court. That the president, particularly this president, must appoint someone who will be just like Sandra Day O'Connor. I don't particularly mind if the president does that, O'Connor was not the worst justice on the court, but he is the president, it is fully his right to appoint for confirmation whomever he pleases. This is one of the president's constitutionally vested functions as chief executive, all presidents have used it for various ends, but never to my recollection to maintain the past composition of the court either in demographics or in ideology.
John Adams used his last days in office to populate the courts with leading Federalist jurists, including the greatest chief justice in the court's history, John Marshall. Why was there no cry upon FDR to replace the retiring or dying conservative justices who were invalidating parts of the New Deal with justices who would continue that practice? Were justices Ginsberg and Breyer (the last two appointments to the court, both by Clinton) demographic and ideological equivalents of those they replaced. The answer, especially in the case of Ginsberg, is obviously not. Any president who must make a Supreme Court appointment must establish a criteria for what they want in a justice and then seek the person who best fits whatever that criteria is, and then appoint that person regardless of superficial (to the job) qualities like race or gender. FDR needed statist yes men who would not invalidate New Deal programs, and he appointed many of them, a whole courts worth of them to be exact. Whatever the criteria, it is the job of the president to make the appointments, and all of them so far have done so on their own terms.
I think that if the president appoints a moderate woman it may be sign that he caved to all the pressure to do so, but perhaps she will represent the best person for the job. It is hard to tell, but a nomination of Alberto Gonzales would be a slap at religious conservatives, while the appointment of a hardline conservative would be a slap at the rest of the country. Republicans are notoriously bad at picking these justices though. Two of the biggest liberals on the court (Stevens - Ford, Souter - Bush) were appointed by Republicans and the only "swing" votes (Kennedy and O'Connor) were both appointed by Reagan. So the way any appointee will end up acting will take a couple of years to decipher.