Ever since a wonderful graduate seminar with Al Martinich five years ago, I've been an intentionalist about interpretation. According to intentionalism, the meaning of an utterance or a text is whatever the author intended to communicate by it. This means that the correct way to interpret texts is to figure out what the author was trying to communicate. Martinich and I hold that this view is correct of utterances and texts of all kinds -- from what you say when ordering at a restaurant, to instruction manuals, to works of literature.
The more conventional opponents of intentionalism are formalists, who believe that the meaning of a text can be determined by the words of the text itself, without recourse to things like the author's intention. (The New Critics were the paradigmatic formalists.) There are also exotic views like reader-response theory, according to which the reader or the interpretive community determines what the text means; and deconstructionism, which seems to hold that texts don't have unified meanings. What I'll try to do here is explain why intentionalism is the best theory of interpretation. I'm going to direct my attacks mostly at formalism here, because it strikes me as the strongest opponent.