I just came across the sentence “George A. Smith became the namesake for St. George, Utah” while editing. A previous editor had changed it to “In 1861 St. George, Utah, became the namesake of George A. Smith.” Slightly awkward wording aside, I preferred the unedited form. Apparently, though, this is an issue of divided usage, with some saying that a namesake is named after someone else, some saying that a namesake is someone after whom someone else is named, some saying that both are correct, and some saying that namesakes simply share the same name without one being named after the other.
But I’d like to get a better idea of which definitions are most common, so I’m putting up this nice little poll. Let me know your feelings on the matter, and feel free to explain your vote in the comments below.