There is some interesting behaviour so far as cat communication with humans. Cats will not meow to other cats unless it's a kitten / mother situation. Meowing with humans is pretty unique.
Wow, good point. Cats usually have this entirely different set of vocal and bodily language when communicating with other cats. Isn't that a sign of higher intelligence? To be able to learn multiple languages. Even if each is fairly small, it's rather fascinating ability to be able to classify your total known language into two distinct sets and knowing which set to use with whom
http://en.wikipedia.org/wiki/Cat_communication#Meow