What's not known is what new features will come with iOS 6, or when it will be released to consumers. Usually, the new software becomes available for download around the time a new iPhone model appears. Apple-watchers expect the next version of the iPhone, the iPhone 5, to appear this fall, about a year after the launch of the 4S model.
In 2010, Apple demonstrated the new iPhone 4 at the WWDC, but analysts don't expect the company to show off a phone model this year.
With the launch of iOS 5 last year, Apple added many features already found in competing smartphone software. It also added the "Siri" virtual assistant feature, which interprets voice commands and talks back to the user.
This year, there are fewer "catch up" features to add, so Apple watchers expect more modest improvements. Some speculate that Facebook could become more tightly integrated, in much the same way that Apple baked Twitter functions into its software last year. That could make it easier to post Facebook status updates from within Apple's apps.
On the Mac software side, there are fewer unknowns. Apple already demonstrated most of the features of OS X 10.8 "Mountain Lion" in February and said it will go on sale late this summer. Developers are already able to download a version of the software. It narrows the gap between the PC and phone software packages, making Mac personal computers work more like iPhones.
Microsoft, Apple's chief competitor in PC software, is on a parallel course. It's set to release Windows 8 later this year, bringing the look and user interface of Windows Phone to PCs.
Cook is also expected to announce new Mac models. Intel Corp. has just updated its processor line with faster, less power-hungry chips, and most of Apple's Mac lines haven't had a major update in a year.
The biggest mystery surrounds Apple's ambitions in television-making. Late company founder Steve Jobs told biographer Walter Isaacson that he wanted to remake the TV. Apple does sell an "Apple TV," but it's small box that connects to a TV to display movies from iTunes. There's much speculation that Apple plans to make a full-blown TV set, integrated with iTunes.
Few company watchers expect Apple to reveal such a set at WWDC, but there's broad speculation that it could make a minor step toward Jobs' goal by releasing updated software for the Apple TV, expanding on its relatively limited functions.