Almost 90 minutes later, Jobs returned to the stage (shown here) to discuss Apple's new iCloud services.
Click on for more slides from the presentation, or for more details, see our live blog and a list related stories.
Other new features in Lion include a new migration tool for Windows users, a Safari reading list, and push notifications, Schiller says.
Most major releases have cost $129. But Lion will be just $29.99, because "we love it so much," he said.
It includes photos you've taken, as well as photos that have been imported to the camera roll through something like Apple's camera accessory. It will use iPhoto on the Mac, the Pictures directory under Windows, and be integrated into Apple TV. (On iOS, the last 1,000 photos are stored.)
You can re-download any of the albums or songs you've bought, Jobs says.