Apple on Wednesday said Steve Jobs would host its annual Worldwide Developers Conference (WWDC) but instead, the keynote will be hosted by senior vice president of Worldwide Product Marketing, Philip Schiller.

The event is set for June 8 - 12 at the Moscone West conference center in San Francisco at 10:00 AM PST.

WWDC will offer in-depth sessions on both iPhone OS 3.0, the world’s most advanced mobile operating system, and Mac OS X Snow Leopard, an even more powerful and refined version of the world’s best desktop operating system and the foundation for future Mac innovation, the company said in a statement.

Apple will spotlight its new iPhone operating system and Macintosh Snow Leopard software at the show, the Cupertino, California-based company said today on its Web site.

Jobs took a leave of absence from day-to-day operations at the company in early January, saying that he needed treatment to manage a “hormone imbalance” that caused him to lose weight throughout 2008. Jobs’ leave is supposed to last six months, which means he may return sometime in July.