Summary: Lion, iOS 5, iCloud highlight WWDC keynote | Computers | Macworld: Apple executives showed off an operating system update planned for next month, teased a mobile OS update slated for the fall, and unveiled a cloud-based service for backing up and syncing documents, photos, and music. The previews came as part of the company’s Worldwide Developers Conference keynote, delivered by Apple CEO Steve Jobs, which kicked off the week-long meeting of iOS and Mac developers in San Francisco.