
Apple, Inc's worth climbed to above $100 billion today in heavy trading. The company is now worth approximately double rival computer maker Dell's market cap ($59.4 billion), but still trails behemoth Microsoft by a hefty margin, whose worth sits at $294.94 billion.
Note that Dell does not compete in as many areas as Apple, and Microsoft competes in more, which helps explain some of the disparity.
AppleInsider attributes part of the surge of Apple's stock price to recent bullish forecasts by some financial analysts, who have raised the 'BUY' price of Apple's stock to $150. Perhaps also contributing to the surge were announcements today of iTunes 7.2 with DRM-free songs.