While we have some form of a common tongue available in Thera, I really only imagine there being a lingua franca available to races with a human/demi-human anatomy (Humans, Elves, Dwarves, Giants, Orcs, Halflings, etc.). The diversity in language among races with completely foreign vocalization is probably wide enough that you would have no way of producing a language that every race could speak. You could play the Fantasy Card at this point and say we suspend disbelief on a number of other matters, but I think racial diversification and making non-human races have a more non-human feel is a good thing. In a serious RP environment I don't think we really don't want "human in a cat suit" and "human in a bird suit" mentality when dealing with other races.