It certainly is unquestionable that since President Clinton left office, the Republicans have been a far superior political machine to the Democrats. And of course, one of the primary benefits of being the party in power is the ability to get your Supreme Court nominee through the Senate approval process and on to the bench. Especially in the last 30 years, as lifespans steadily lengthen, this is a privilege that is rarely granted. President Clinton nominated two in his eight years; Ginsburg and Breyer. The current President Bush nominated none in his first term. His father was able to nominate two: Thomas and Souter.
But why is it such a privilege? Well, with only nine justices on the court, a single nomination can drastically change the structure of the court. For example, the test that everyone always talks about is Roe V. Wade; that is, the question of whether the right for a woman to have an abortion is one that should be protected by the federal government. The conservatives would like to see it overturned, while the liberals would be appalled. But the question then becomes: what would it take to overturn this decision? Is it just a matter of getting enough folks onto the supreme court who disapprove of abortion?
Well, it isn't. (Or at least, it shouldn't be.) See, when the court decided Roe v. Wade, they looked at a lot of different things: Historical precedents. Decisions made in other trials. Rights of the individual versus the interests of the state. Changing a decision made by the highest court of the land isn't just a question of getting five people up there who happen to think that abortion is icky. And even if you did, maybe a future liberal president might get lucky and nominate a couple of others who would swing the decision right back around again. So the issue that the conservatives should be trying to deal with is, "How do we get the decision changed in such a way that it won't be overruled by the next court?"
Here's how: Write up the decision in such a clear way, with such incisive reasoning, that it is very difficult for opponents to contradict. To do that, you have to have a brilliant conservative scholar on the bench; someone who's known to write impeccable, incisive decisions on the bench.
Harriet Miers will be confirmed; I don't have any doubt of that. Enough Republicans unwilling to contradict their president, coupled with enough Democrats thinking that she is the best they will get, will vote for her to get her through. She may be a good conservative, and vote the way the President hopes she'll vote. But there is surely no evidence to support the idea that she will be a shining conservative light; a justice who will write decisions both for the majority and in the dissent that will be referred to by future scholars and judges as a guiding path for the ages. This is what conservatives really wanted on the supreme court, and this is, with 99% certainty, what they did not get.