JUST when you thought no one could make any more money by codifying the obvious, Michael Porter is back. Probably the nation's leading name-brand business-school professor and management consultant, Porter teaches at Harvard and advises companies on the side through his consulting firm Monitor, which today's freshly minted MBAs consider a "hot shop" to work at. His several books over the last decade include Competitive Strategy and Competitive Advantage, and they have established him firmly in the pantheon of management-strategy gurus. Indeed, many of the MBAs who roam your neighborhood today were weaned on the "Porter model" of how industries should be analyzed and how companies can best compete.