An interesting review of a new academic book on ETs ponders that question and others (Andrz Kukla. Extraterrestrials: A Philosophical Perspective. Lexington Books, 2010). The last part of the review notes the following:

In the final and most difficult part of the monograph argues that even if we grant all the most optimistic interpretations about the extraterrestrial intelligence, if, as is argued by Noam Chomsky and his followers, human language is based on some evolved neural substrate, then we could not ever learn their language. This would be true whether or not the pre-diaspora ancestors of modern humans already spoke a grammatically rich language, or something more primitive. A language with a completely different evolutionary history could never be learned by human beings.

Speaking of communication . . . I need to get back to Milor vs. Bates.