It looks as if Justice Souter will be retiring at the end of this term or when his replacement is announced. Most people probably know that President Obama used to teach constitutional law at the University of Chicago. Last spring Ed Whelan looked at his understanding of the Constitution and the type of justice he will appoint. The nominee will undoubtedly be a "living-Constitutionalist" and pro-abortion-rights like Justices Stevens, Souter, Ginsburg, Breyer, and (often) Kennedy.
One small but safe prediction: no matter who is nominated, and no matter how radical is their record on abortion, some Evangelical and Catholic supporters of Obama will claim that the nomination will somehow reduce abortion.