Overnight WOR-AM radio show host Jean Shepherd asked his listeners ("the Night People") to go into bookstores and ask for a book that didn't exist. Armed with a fictitious title and author, along with a vague plot outline, the Night People got their hooks in wherever they could. Fueled by bewildered bookstore owners and distributors, I, Libertine eventually did end up as a genuine bestseller.
According to a later interview with Shepherd (mp3), the hoax was targeted at New Yorkers' obsession with lists and rankings. Ballantine Books hired Theodore Sturgeon to write the novel itself (he banged out a draft, then one of the Ballantines finished it) (1956). Kelly Freas did the jokey cover (pictured here, thanks to Wikimedia). So the paperback entered the circulatory system of bookselling and book owning, the hoax entering real life, Tlön landing on Earth.
Another story to file under alternate reality game antecedents.