To a certain extent having a Wikipedia biography defines someone today as being noteworthy. And in classic recursive fashion there's a Wikipedia page that tries to define just how notable, and in what ways, a person should be in order to merit such a biography. The discussion on that page is interesting, perhaps even fascinating, but although the guidelines try to be clear-cut they still (to my mind at least) leave a great deal of leeway.

Back a couple of generations ago we had a number of more or less clear-cut ways of determining whether someone was noteworthy. We were, for instance, told that "a title on the door rates a Bigelow on the floor". This, of course, was meant as a status symbol: having a Bigelow carpet was something you deserved if you'd made it, so conversely, if you had such a carpet people understood that you'd made it. Today people who've made it have their Wikipedia biographies, so there are people who expect, or at least hope, that if they can get a Wikipedia biography they'll be on the road toward "really" making it. It's a nice idea, though I tend to doubt that it works very often.