Ever since Justice O'Connor retired, the makeup of the Supreme Court has been a bit of an enigma. Some consider the court packed with hard-line right wingers, minus a few stalwart centerist holdouts. Indeed, when Justice Stevens is now the most liberal member, it's clear that the court is predominantly conservative. But is it really? We already know that Scalia, Thomas and Roberts are the conservative foundation, with Alito probably squarely in their camp as well (although I am not yet sure what to make of him). We also know that Breyer, Ginsburg, and Stevens usually find themselves at odds with the other four (although I will not concede that they are, as a result, 'liberal'). Souter seems squarely in the middle, and much like Stevens was in the 70s and 80s, Souter seems to be the apolitical moderating force on the court. Nevertheless, Souter seems to be much less conservative than expected when he was nominated by Bush Sr., and many consider him part of what is now the liberal side of the court. Despite this movement to the right, there still appears to be a 4-4 faction; still much room for contention on the supreme court.
An then there is Kennedy. What to make of Justice Kennedy. Indeed, he is a bit of an enigma on the court, sometimes siding with the liberals (gay rights), and other times siding with the conservatives (abortion). In the wake of Gonzales v Carhart, it seems that Kennedy may indeed take O'Connor's place as the swing vote on the court, such as it is.
A very good article on this subject from Slate.com can be found here. I don't necessarily find it troubling that our supreme court has become more conservative over the past 20 years or so, as long as there is some balance. There are good arguments that the very liberal Warren court may have done more harm than good, even if I do find much of their activism attractive. A homogenous court is probably much more dangerous than a balanced one, and right now, such as it is, we seem to have some balance left. I do hope that Stevens can hold out for at least two more years. The thought of Bush nominating another member of the court makes me shudder (it's not a republican thing, mind you, it's a Bush thing).