Update: Microsoft sent out the press release this morning. Read it here.
While no official press release has been sent out by Microsoft there have been 3 flyers now that call for a price drop on the Xbox 360 on August 12th. Wal-Mart, Toys R Us, and now Circuit City.
Since an official announcement has not been made by MS it's still possible that this is one elaborate hoax. However, with rumors coming out before E3 and now 3 different flyers this is either a VERY elaborate campaign or it's the real deal.
Either way, I recommend that people in the market for a 360 wait a couple of weeks and see if this gets confirmed. A hard date has been given so a confirmation will come soon before August 12th.
With this price drop the value proposition of the Core pack decreases even further. If Microsoft does not decrease the price of the hard drives then a Core + HDD will cost more than a premium by itself. Considering you get a lot more with the Premium the Core just doesn't make sense to anyone.