Fr. Edward T. Oakes has a rumination on Rene Girard and the Atonement over at the First Things blog.
I’ve only read Girard’s I See Satan Fall Like Lightning, but found it very thought-provoking. However, I think Fr. Oakes is on to something when he points out that Girard can’t make sense of the traditional idea that God was at work in the Cross of Christ. I also can’t help but think that Girard’s scheme of mimesis-and-scapegoating offers a reductive understanding of (non-Christian) religions. Though my knowledge of his work is admittedly limited.