According to a report posted by MobileCrunch, AT&T has commenced rolling back its upgrade eligibility dates for some iPhone customers from November 21 to June 21st.

This morning they received a report from a reader who received following upgrade message from Apple:

Not sure if anyone [..] has noticed this same thing, but my Upgrade Eligibility date on my AT&T account switched from 11/21 to 6/21 in the last day or so. I bought a 3GS on launch day last year, and my upgrade date read 11/21 since then. A few other folks in my office have noticed the same changes happening to their accounts as well.

It is still not clear whether if this is an unintentional leak or AT&T has slowly started rolling out the changes across their database.

The rumors are hot that Apple is expected to announce and possibly ship the iPhone in June. If the past history has anything to do, the company announced its previous models at WWDC. A rumor earlier this month also hinted that since Apple has booked the Yerba Buena Center for Arts by the Moscone Center in San Francisco for June 22 which may be yet another possible venue and release date for Next Generation iPhone, one day after the upgrade eligibility date of June 21.

Apple Tablet Announcement: Yerba Buena Center

Traditionally, Apple has launched every single previous iPhone on a Friday. Friday launches are all about the numbers: less people work on weekends, meaning more people have time to buy the iPhone in the first 3 days.It’s worth noting that it would mean slightly bucking of tradition this time, as June 22 is a Tuesday, the day the Yerba Buena Center for Arts has been booked by Apple.

Now the big question: Has the big event is set for June 7 or 21 ?  What do you think ? Share your opinion with us?   [Via iClarified]