Dear Rich Staff. After all, the folks over at Yahoo Answers seem to have already addressed this issue. Oh wait, we see why ... because the Best Yahoo Answer kind of sucks. We're guessing it's the 'Best Answer' because it's the answer that best suits the needs of the person asking the question. Oh well, it will all be over soon!
Right, you had a question. A few months ago we answered a question about using lyrics in a book, and for the most part, the same rules apply when using lyrics in connection with artwork. Limited use of lyrics -- perhaps four or five lines -- may be excused as a fair use. But more extensive quoting of the lyrics requires permission. Of course, if you're just doing a one-of-a-kind artwork, it's unlikely to be an issue (unless you write to the lyricist to share your excitement). But if you're mass producing posters with lyrics and distributing them via the web, you're more likely to trigger a cease and desist letter.