SAN FRANCISCO â€" It’s game day at the Apple Worldwide Developers Conference, the company’s annual event for app-builders and engineers.

The line to enter the Moscone Center, where the conference is being held, stretched almost two blocks as thousands of Apple faithful waited to enter the convention center.

What will these Apple fans see today? Rumors are swirling of an entirely new design for Apple’s iOS operating system that is both sleek and flat. Timothy D. Cook, the company’s chief executive, might unveil a new music service and some MacBook computers. There are even rumblings that Sir Jonathan Ive, Apple’s head of design, will grace the stage.

12:29 P.M. Crowd Filing Into Moscone Center

We’re finally seated in the auditorium. The song “Let’s Go,” by Matt & Kim, is playing on the loudspeakers as thousands of people are rushing to grab their seats. In the hallway outside some large billboards are shrouded in black cloth, presumably hiding some of the new products we will see when the Apple event begins in 30 minutes.

â€" Nick Bilton