Ohhhh, what a Zen question, like the one hand clapping! I'll have to ponder this. It *is* very interesting.
I have also noted that my kitties don't notice mirrors per se, but they seem to know that the others' reflections are not real cats.
And I've also noticed what Jeanie discussed about modeling. Mozart is our first cat, and he spent 1 mth alone with us before we adopted again. He was about 8 wks old then. We get the distinct impression that he thinks he's a person sometimes.