The Moscone Center has posted its schedule for June and July of 2010, and an unobtrusive and cryptically unspecified entry for a "Corporate Event" may be a placeholder for Apple's 2010 World Wide Developer Conference (WWDC), as noted by TUAW. Apple has not as yet announced WWDC 2010, but the "Corporate Event" is scheduled from June 28th to July 2nd.
The June time frame has long been Apple's preferred date for the WWDC for some time, though the development and release schedule of specific operating systems has pushed the event as late as August, as was the case for WWDC 2006. It would be remiss of us to not point out that the iPhone was officially released on June 29th, 2007, and it was June 8th, 2009 that Apple released the current iPhone, the iPhone 3GS.
With the weeks surrounding the "Corporate Event" at the Moscone booked by other, named corporations and trade groups, the betting money is likely to be Apple the "Corporate" of that scheduled "Event."
A screenshot from the Moscone Center's Web site