Folks at Microsoft believe it is an absolute necessity that Sony start creating a low-end package for the PS3 and get it out there quick. They believe if the Christmas season is less than stellar, you can stick a fork in the PS3.
The old 60 GB SKU is being cleared out for $499 as quickly as possible - as you might recall, this was the supposed "price cut" that Sony announced. In reality, once supplies are gone in the next couple of months it'll be gone forever. However, that doesn't leave Sony in a good place. A single, $599 SKU would be untenable; if they don't move significant hardware this holiday they'll basically be dead for this generation.