David Bernstein and Ilya Somin make it.
I agree with Bernstein generally, but this is a key point, I think:
Libertarians have been heavily involved in some of the most important constitutional Supreme Court litigation of the last two decades, either in terms of bringing the case, being among the most important advocates of one side's constitutional theory, or both. Among the cases in this category are Lopez, Morrison, Boy Scouts v. Dale, U.S. Term Limits, Grutter, Gratz, Kelo, Raich, Heller, and probably a few more that I'm not thinking of offhand. With the minor exception of Justice Breyers' vote in Gratz, in each of these cases, the ONLY votes the libertarian side received were from Republican appointees, and all of the Democrat appointees, plus the more liberal Republican appointees, ALWAYS voted against the libertarian side. The latter did so even in cases in which their political preferences were either irrelevant (Term Limits), or should have led them to sympathize with the plaintiff (Lopez, Kelo, Raich).
The only exception to this pattern is Lawrence v. Texas, in which Justice Kennedy seems to have been influenced by the Cato Institute's brief. But if the liberals had been able to muster five votes without Kennedy, I'm sure the opinion would have been quite different, less libertarian and more about "tiers of scrutiny" and whatnot. I'm a law professor, teach constitutional law, and the subject is dear to my heart. I'd much rather have the side that tends to take my ideological compatriots' constitutional arguments seriously on the Court. And Raich and Kelo, respectively, suggest that the liberals on the Court not only don't take libertarian arguments seriously, they don't believe in (a) any limits in federal regulatory power, whatsoever; or in (b) property rights, even when big corporations are using the political process to screw over the little guy.
I also agree with Ilya that it's very important to have divided government right now, at least as much as a pseudo-Democrat in the White House will provide that.
Considering how many vacancies there are in the lower courts because of Bush's appointees being blocked by the Democrats in the Senate these last 8 years, an Obama/Pelosi/Reid Axis could appoint a whole swath of Lefist judges immediately upon taking office. They wouldn't have to wait for anyone to retire to pack the Courts.