According to Rob (since I was not there to see it) Rowan reached her hand out to Merry for the first time.  He was walking by, and she reached out to him, and he let her touch him as he continued to walk by.  My current prediction re: how the cats will behave toward a grasping baby is that Merry will adapt and be generally okay with it and Pippin will hide and stay away as much as possible.  We'll see!