What's up with the "Proust questionaire" in every issue of Vanity Fair?

Okay, embarassing for a comparative literature major to admit, but I’ve never actually read any Proust. In every issue of Vanity Fair magazine, the last page is called the “Proust Questionaire” and a different famous person in each issue is asked to answer the same questions, such as, “what is your idea of perfect happiness,” “what is your greatest extravagance,” etc. Can anyone explain the Proust reference to me?