O'Connor's Swan Song?
It really hits the fan when Gonzales v Carhart reaches the Court. This case will examine the 2003 ban on partial birth abortions. The last partial birth abortion case, Stenberg v Carhart, was a 5-4 decision with O'Connor joining the liberals to strike down the law. Having Alito replace O'Connor could shift it 5-4 the other way and uphold the ban. Based on his dissent in Stenberg, Justice Kennedy seems like a very firm vote to uphold the bans under the Casey test.
EDIT: A few Volokh commenters think that there is more going on here than generally thought. This might be a sign that the Court is going away from facial challenges of statutes. Facial challenges rarely succeed, and the Court is more likely to pick apart a law in an as applied challenge. This is part of the reason why Wisconsin Right to Life v Federal Election Commission may come out differently than McConnell (Right to Life is as applied, McConnell was facial).