SAN FRANCISCO (MarketWatch) - Technology stocks tumbled at the opening bell on Wednesday as the broader market retreated on lingering economic concerns despite the recent Federal rate cut. The Nasdaq Composite Index and the Morgan Stanley High Tech 35 Index were both off 1.5%,while the Philadelphia Semiconductor Index was behind 1.7%. Apple Inc. led the retreat, falling more than 5.5% after the company announced that CEO Steve Jobs will not give the keynote at next month's Macworld Expo in San Francisco. The Dow Jones Industrial Average (DJIA:
