Steve Jobs will keynote the 2008 World Wide Developers conference, which is a sure sign of something big to come from Apple. We’re hoping it’s going to be the release of the 3G iPhone. What else could it be? A thinner MacBook? Not likely. Apple PR confirmed to Fortune that Jobs will headline the event, prompting Piper Jaffray analyst Gene Munster to write “The launch of the new model is imminent” in a report to clients Monday. Munster notes that first-gen iPhones are now unavailable via Apple’s U.S. online store as of May 10, which he says points to the firm clearing inventory in advance of an upgraded model.