Apple's stock touched $600 for the first time, the day before the company's latest iPad goes on sale. The stock reached $600.01 just after the market opened and was up $3.76 at $593.34 after the half-hour of trading. Apple is the world's most valuable company, with a market capitalization of nearly $555 billion. It topped $500 billion for the first time in late February, a market value peak where few companies have ventured. Anticipation is high for Apple's latest creation; some industry experts believe the company could sell 1 million of the new iPad tomorrow. Click for reviews.