Ronald Reagan extols them. Venture capitalists lavish money on them. They seem to be everywhere, starting their own companies, making megabucks in everything from computers to package-delivery services, and turning up on talk shows as the new Beautiful People of the 1980s.
They are the entrepreneurs, and their current success can be threatening to established corporations. At a time of rapid technological change, young, fleet-footed firms with a new product or a new way of selling can quickly take over markets. Some of the most important breakthroughs in recent years in such fields as semiconductors and bioengineering have been made by...