Apple CEO Steve Jobs — who has been on medical leave since January — takes the stage this morning to make some major announcements, and while Apple officials sent out a news release last week tipping their hand about what he’s revealing, the company’s been tight-lipped on the details.

iCloud: Probably the most exciting reveal in today’s speech, Apple’s new iCloud service is expected to include some kind of streaming iTunes capability.

But Daring Fireball’s John Gruber — a trusted blogger on all things Apple — says he believes there’s more to it than that. “Music storage is a feature of iCloud; iCloud is not a music service,” he wrote in his latest post.

He said he believes that iCloud could be a game-changing move away from relying on USB ports and cables to update your media library.

The new iCloud may be a revamped version of Apple’s MobileMe service, hosts documents, e-mail and calendar information for $99 per year.

Having iTunes in the cloud would likely mean remote access to your music from any computer, and the ability to play and manage your iTunes media from anywhere.

Lion:  Latest rumors from 9 to 5 Mac indicate that Apple may be planning a June 14th launch of Lion. While Apple’s said that it’s planning a summer launch of the operating system, that would be much earlier than most have expected.

As for features, Apple has already given a sneak peek at the next big operating system. The system is said to be more app-heavy and feature a navigation screen called Launchpad, a menu that shows users all of their apps.

In earlier previews, Apple announced that Lion will have Resume, which will restore your Mac to the way it was when you restart it or quit an application for an update; AirDrop for wireless file transfers.

And navigation will be funneled through something called Mission Control, a mix of Expose, Dashboard and Spaces.

iOS 5: Reports have said that iOS 5 will have a revamped notification system and new widgets, but there’s been precious little said about iOS 5 in general. A screenshot that went up on TechCrunch over the weekend shows notifications being posted at the top and center of the home screen, instead of floating over the middle.

“Could it be? Is this it? iOS 5?! I honestly have absolutely no clue. But it certainly seems like it at least could have the right idea,” wrote MG Siegler, hedging his bets.

There have also been reports that, starting with iOS 5, Apple will release updates over the air instead of making users hook up to their computers for updates through iTunes.

One more thing?: We’re sure Apple will making major software announcements today — but what about hardware? The company has a history of announcing some model of the iPhone at WWDC, but there seems to be no indication of a phone announcement this year. Many reports have indicated that the next iPhone won’t be out until September.

People are still hoping, however, that we’ll see a new gadget today. There are rumors of a upgraded iPhone 4, the iPhone 4S, being announced today.

Jobs has a history, after all, of surprising with big announcements. All we know for sure is that all will be revealed once his speech starts at 1 p.m. Eastern time.

Let us know: What do you think will be the most important developments from WWDC?

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