Apple’s Worldwide Developers Conference (WWDC) Web site was updated today with news that all attendees to the event will receive a free copy of O’Reilly’s new book, “Cocoa In A Nutshell.” WWDC will be held June 23-28 at the Moscone Center in San Francisco. The event will feature a keynote by Apple CEO Steve Jobs, who is expected to unveil Mac OS X “Panther.”