SAN FRANCISCO -- The banners are already flying in downtown San Francisco for Apple as it gathers its most faithful this week for its annual Worldwide Developers' Conference -- the event where the tech giant typically unveils its latest operating systems and maps out it ambitions for the year.

At the convention center where Apple stages its big show, posters displaying nothing but a simple "8" hang from the ceiling -- all but confirming that we will see the next version of its mobile software, iOS 8. Analysts say that it's also more or less a given that Apple will show off a new version of its Mac operating system, which may get a visual makeover to match its mobile sibling. (Apple completely redesigned the look of iOS last year, to mixed reviews.)

But Apple is still keeping a lid on some of its impending announcements, adhering to its reputation for secrecy. Other banners in the building remain covered in black cloth.

Analyst predictions and good, old-fashioned fan speculation have thrown up several ideas for what may be behind the screens. The more likely possibilities, analysts say, include an announcement of a new health data app, Healthbook, that will let Apple users pull fitness data from partnering products into a central hub on their phones. There's also speculation for a similar partnership hub for home automation, which would let people more easily control things such as their thermostat with an app on their smartphone. Other, smaller forecasts include an update to Apple's troubled Maps app and new functions for the iPad that may let users run two programs simultaneously.

The wilder predictions include suspicion that Apple may announce some sort of new gadget at the conference, which has focused much more heavily on software in recent years -- with some big dreamers hoping for the long-rumored "iWatch," Apple's expected entrant into the wearable tech world. But most analysts say that it's unlikely we'll see a new device Monday, when Apple chief executive Tim Cook takes the stage for the conference's big keynote.

Still, Apple -- normally very quiet -- has certainly set high expectations for itself headed into the conference. The company has already made plenty of news this month. Apple announced just last week that it would acquire Beats Music and Beats Electronics in a $3 billion deal that came with the company's two top executives, Jimmy Iovine and Dr. Dre. Apple executives have also hinted, broadly, that they're sitting on an interesting new lineup of products.

Eddy Cue, Apple's senior vice president of software and services, told attendees at last week's Code conference that the company has the "best product pipeline" in 25 years. That's a big promise -- one that Apple may start delivering on today.