Jobs reveals iCloud

Apple CEO Steve Jobs has made a brief appearance at the company's Worldwide Developers' Conference to unveil the iCloud, a free, hosted service that allows users to sync content stored in Apple applications across multiple devices.

Specifically, Apple users will be able to sync their music (iTunes), photos (iPhoto), documents (Pages, Numbers, Keynote), downloaded apps, mail, contacts and calendar appointments via a content-sharing service hosted in three Apple-owned U.S. data centres.

It also acts as an automated backup service for iOS devices whenever they are plugged in to recharge.

Apple is offering 5GB of iCloud storage free, and will not count content purchased from the vendor. Pricing beyond the 5GB is yet to be unveiled.

The company hopes the service will power its next stage of growth and popularise Web-based consumer services. It claims to have spent nearly US$500 million on a new data centre to support the service.

Apple's new data centre in North Carolina

A still thin-looking Jobs walked out to a standing ovation from the more than 5,000 Apple faithful in downtown San Francisco's Moscone Center, making opening comments for just a few minutes before ceding the stage to marketing chief Phil Schiller.

The Silicon Valley icon emerged from medical leave to launch the Internet-based service, which lets users play their music and get access to their data from any Apple device -- a crucial capability for users increasingly accustomed to performing tasks on the move.

PIE IN THE SKY

The iCloud announcement also marked the elimination of MobileMe, which had the dubious distinction of being among the few Apple products that failed to take off.

Jobs said people will be able to share book purchases, music and data in general, such as calendar items, across different devices, while backing up and updating information regularly.

Apple's expansion into cloud computing comes as the company strives to stay a step ahead of rivals such as Google and Amazon.com in the mobile and online content business.

It could ignite more demand for devices such as the iPhone to the iPad, while helping sales of music through iTunes.

More than 25 million iPads sold in the 14 months since the tablet computer was launched, software chief Scott Forstall told the crowd. And customers have bought more than 15 billion songs from iTunes, the world's biggest music store.

Apple also introduced software upgrades at the conference, including Lion, its Mac OS X computer operating system and the next version of its mobile operating system.

New features demonstrated included an improved email infrastructure and multi-touch features for the Macintosh operating software.

For the iPhone and iPad, executives described how the fifth version of the iOS software will feature drop-down notifications for everything from Twitter feeds to Facebook alerts, and new applications such as Safari tab browsing.

Jobs' decision to headline the event assuaged some concerns on Wall Street about his health. Monday was only his second appearance in public on his company's behalf since he went on medical leave in January.

(Writing by Edwin Chan. Editing by Robert MacMillan).