Thomas Cathcart and Daniel Klein, Plato and a Platypus Walk into a Bar . . . Understanding Philosophy Through Jokes, Abrams Image 2007, pp. 183-184:
Contemporary philosopher William Vallicella writes, "Metaphilosophy is the philosophy of philosophy. It is itself a branch of philosophy, unlike the philosophy of science, which is not a branch of science, or the philosophy of religion, which is not a branch of religion."
It is statements like this that have made Vallicella such a hot ticket on the party circuit.
I haven't read the book, so I can't tell you what I think of it. The only reason I know about the above citation is because Dymphna of Gates of Vienna drew it to my attention.