Apple's annual flagship event, the Worldwide Developers Conference (WWDC), kicked off today at 10 a.m. (PST) and the atmosphere is electrifying as the world awaits the presentation of Apple's latest software and services viz. iOS 5, OS X Lion and iCloud from the world's greatest showman and tech guru Steve Jobs.

The man in black turtleneck t-shirt and jeans is making a rare appearance today to deliver the keynote address.

Jobs, who survived a rare pancreatic cancer in 2004, hasn't been keeping well in recent years. In 2009, he took a 6-month medical leave and got a liver transplant done. Earlier this year in January, Jobs again took a medical leave, leaving Apple at the charge of COO Tim Cook.

In March, Jobs made a surprise appearance to take the wraps off iPad 2 and since then he went into hiding, allowing the media to publish speculative reports on the condition of his health.

However, on Monday, all speculation will be put to rest as the world will once again see Jobs in flesh.

Jobs' appearance as the keynote speaker at WWDC will be watched keenly by Apple fans and investors alike as the world's largest technology company's success is tied to its co-founder.

No wonder, every time Jobs' health concerns have emerged, Apple stocks have taken a hammering.

On the other hand, after it was announced that Jobs will be the keynote speaker of WWDC 2011, 5000-odd tickets for the 5-day event was reportedly sold out within 10 hours of being placed on sale on March 28, despite the hefty price tag (about $1,600).

The WWDC has traditionally been used over the years by Apple as the venue to announce major changes in its products, software or services. And Jobs has almost always been the keynote speaker in the past decade (he did not attend the 2009 WWDC event).

Meanwhile, though for the last couple of years, Apple has been presenting the new iPhone at WWDC though it is believed that it may not be doing so this time.

The major draw of WWDC 2011, Apple said, will be the latest Mac OS X 10.7 (dubbed Lion), the next version of mobile operating system iOS 5, and the new cloud-based music, photo and video service - the iCloud.

While OS X Lion will be more app-focused and app-friendly, iOS 5 is expected to feature better navigation system, automatic sync system that runs on background, easier file organizing system, near-field communication (NFC), and some widgets on unlock screen.

iOS 5 is also expected to feature genuine multitasking capabilities , faster over-the-air updates for apps, improved notifications capabilities, enhanced widget capabilities and better speech recognition features.

Twitter integration that goes beyond basic features like photo sharing and sending tweets has also not been ruled out.     

As for iCloud, analysts are going gaga over it, saying it could kill rival services offered by Google and Amazon.

The revolutionary iCloud, unlike Google's Music Beta digital locker or Amazon's Cloud Drive, which requires users to upload their songs or data, will be able to scan a user's library and make mirror copies available instantly.

iCloud users will be able to stream music to their devices, by matching the song's ID within Apple's archives, without having to upload their library onto Apple's servers.

The convenience, simplicity, and discoverability of iCloud will make it a major draw for both music/film publishers who are seeking to minimize piracy, while protecting their economics in a hosted model, RBC analyst Mike Abramsky said.

Moreover, it will give Apple massive computing power to achieve numerous things that were not possible before, analyst firm Zacks Equity Research said. Transfer of the storage function to the cloud would also be beneficial for Apple, since this could lower hardware costs. Device speed would also increase, the company said in a blog.

Over to Apple and Steve Jobs.