I think Orin's take on Slate's Dahlia Lithwick is quite right, both on the positive and on the negative. One other item from her column I noticed:

And an excerpt from the new book by Ann Coulter's breasts suggests that he is somehow responsible for the ban on prayer in public schools.

Now I've disagreed with a great deal of what Ann Coulter has said (though I generally try not to bring up her breasts in the process). But I don't quite see the aptness of Lithwick's criticism. Here's the linked-to paragraph from Ann Coulter's column, which is also the only mention of Justice Kennedy in that column:

Among the things the Supreme Court has held "unconstitutional" are prayer in public schools, moments of silence in public schools (which the Court cleverly recognized as an invidious invitation to engage in "silent prayer"), and displays of the Ten Commandments in public schools. In 1992, the Court ruled it "unconstitutional" for a Reform rabbi to give a nonsectarian invocation at a high school graduation ceremony on the perfectly plausible grounds that Rhode Island was trying to establish Reform Judaism as the official state religion. (Opinion by Justice Anthony Kennedy.)

Ann Coulter starts out by talking about the school prayer cases and some other cases. Then she moves on to talk about the graduation prayer case, and correctly notes that this case was written by Justice Kennedy. Coulter is certainly faulting Justice Kennedy's position on graduation prayer, but for the life of me I can't see how she's "suggest[ing] that [Justice Kennedy] is somehow responsible for the ban on prayer in public schools."

Lithwick's work is always very readable, and sometimes quite incisive. But at times she seems to write with less care than the subject deserves, and with not enough attention to possible weaknesses in her argument.