It's hard to prove ghost-writing, but the circumstantial evidence is strong. Obama has no history of high-quality writing other than the books that he wrote when he met Ayers. Even though Obama came from an island state and an island nation where you might expect a high amount of water exposure and experience, Obama has not offered up any history as a youth of engaging in boating, fishing, surfing, or any interest in the sea at all.
If, with that background, I'm asked to believe that he's exceptional in the use of nautical metaphors strictly from research alone, it's a leap that I need more convincing to take.
-PJ
To get back to Shakespeare and Lanier, though: not all of Shakespeare's rich imagery comes from the field of music, does it? He drew from many fields, didn't he? And in some of those fields it would be hard for a woman to acquire first-hand knowledge in the 16th or 17th century.
I'm not saying a woman absolutely couldn't have written the plays, but it's at least as likely that "William Shakespeare" could have come to know something of music, farming, war, navigation and other fields as it is that Lanier could have. Also, the bawdy puns in the plays are, all things considered, less likely to come from a woman than from a man.