It is no secret that Apple has historically released major iPhone OS updates at the same time as new iPhone hardware. This was true of both the iPhone 3GS and the iPhone 3G. They were also released sometime in the June (or early July) in previous years. Now more evidence of an iPhone HD launch happening in June has surfaced. According to Boy Genius Report, their sources are claiming that AT&T is blocking employee vacations for the entire month of June.

Same story as last year and the year before, but we’ve confirmed with multiple AT&T sources that the carrier has now put a block on employees taking vacations in June. The only time AT&T does a straight block like this is for iPhone launches. What’s interesting is, if AT&T is blocking June, perhaps the iPhone will launch a little earlier than July this year.

Apple has apparently booked a date to use the Yerba Buena Center for Arts, which is a popular location for their new product announcements. The date they reserved is on June 22, which seems to fit perfectly in line with the earlier rumor from Engadget. Since Apple has already announced that iPhone OS 4 would be released this summer, an iPhone HD launch sometime in June seems to make sense. We won’t know for sure until then, but there will certainly be a lot more rumors circulating as summer approaches.