We've spent the last hour on the phone calling up random Target stores around the continental United States to nail this story down. What we can say at this point is that certain Target stores do currently have the $499 price on the PS3 (Item# 207230001). Beyond confirmation at these stores, in one case we even have a copy of a person's receipt, dated today, for a PS3 at $499.99. We've even asked while going through the price check process if there is a pattern to the Target computers and why we would be getting different prices at different stores -- there was no adequate answer.
At this point we don't know if this indicates that the price drop may begin this week, or if somebody flipped a switch at the wrong time. We've received reports that certain Circuit City stores have also started selling the PS3 at the $499 price, before their alleged sale next week, but we currently can't confirm that. Even if Sony doesn't announce a PS3 price drop at next week's press conference, it looks like the retailers are moving ahead with one anyway.
[Thanks Nathan and Counter5th]