David Lipsky got his book launched with plenty of buzz. His publisher was foursquare behind him. And the opening round of publicity created aa run of sales any publisher would envy. One problem? You can’t buy the book anywhere. Lipsky’s book sold out of its first printing of 40,000, and making more takes three weeks or longer. By then, will people stiull be lining up to buy it? The story shows how cautious publishers have become…