Internet Capital Group and IBM Corp. are to launch an intellectual property exchange in Wayne, Pa. The as-yet-unnamed exchange, due by September, will allow companies to bid on patents and other intellectual property, something now done mostly off line. Still, the opportunities are gargantuan; published estimates put the intellectual property marketplace at $100 billion. Internet Capital and IBM face entrenched competition; PricewaterhouseCoopers L.L.P. last year launched its own intellectual property exchange.