Will actually be the same week as E3
As we have been speculating based on whispers from our sources, Apple has confirmed that their upcoming Worldwide Developers Conference will take place from June 6th to the 9th in San Francisco. Ironically, this is the same week as E3, which could present a conflict for some developers.
Apple says that they will be focusing on the future of the iOS and the Mac OS at the event. It is likely that Apple will announce an actual release date for the next versions of the iOS and Mac OS at the event and provide a significant amount of information on what will be included in the next releases.
It has not been uncommon for Apple to schedule events at the same time other events are happening. Most recently, the company revealed the iPad 2 just down the road from GDC. In this case, however, because so many developers attend E3, it could make things interesting; Apple has been putting a lot of effort into the gaming and entertainment value of the iOS devices as of late, so it would seem that they are hopeful that developers will attend the WWDC, rather than E3, or split time between the two events.