WWDC has been a primarily software driven event for the past few years, there have been hardware announcements but only for the mac line (Retina MBP's, new Mac Pro etc), the iOS device line has been moved to a Q3 event. We might see a new line of hardware or a hardware refresh at this event, but we won't see any new iPhones or iPads just yet.
WWDC is all about giving developers the information they need to develop software for the next releases of Apples operating systems over the course of a week long event, they keynote is still normally pretty interesting but for developer like myself it's the rest of the week thats the real interesting bit.