Apple CEO Steve Jobs seemed fit when he explained Apple's new iCloud service at the World Wide Developers Conference at the Moscone Center in San Fancisco on Monday afternoon, but his appearance has grown alarmingly frail. Apple shares dropped 1.57 percent on Monday, and two-thirds of that decline took place after Jobs took the stage.

Apple CEO Steve Jobs speaks at the company's World Wide Developers Conference at the Moscone Center in San Fancisco on Monday. Inserts show Jobs on March 2 at the launch of the iPad 2 and on Monday. /AP-Yonhap

◆ Strong Delivery

The CEO's appearance and delivery seemed to underscore Apple's strengths and weaknesses. Jobs spent 40 minutes explaining Apple's new iCloud service, which enables users to store music, pictures, e-mail addresses and other information on the Internet and retrieve them anywhere using their Apple gadgets.

His delivery got high marks. The Washington Post said while Apple is not the first to offer cloud computing services, it would improve convenience for iPhone and iPad users. Apple also got high marks for unveiling the iOS5 operating system for smartphones and the OS X Lion OS for the Mac PC.

◆ Uncertainties

But the market gave Jobs failing marks for health. Jobs appeared weaker judging by his voice and the duration of his presentation. Jobs was on stage for exactly 42 minutes, which is long enough but shorter than any of his previous presentations, which have often lasted more than an hour.

Jobs had led Apple while undergoing surgery in 2004 for pancreatic cancer and receiving a liver transplant in 2009, but went on indefinite sick leave in January. Monday's appearance was his second since his sick leave following the unveiling of the iPad 2 in March.

The problem is that Jobs rules supreme at Apple. According to Fortune magazine, Jobs decides how to respond to media reports and even determines the menu at the company's pantry and the design of the company buses. Without him, the market appears to feel that the firm will be rudderless.