The introduction of new SKUs doesn't necessarily mean a clearance sale for the older SKUs. Even when the Slim came out, the old 80gb models were "clearanced" for $299, if I recall correctly. Though stores quite often had their own sales below Sony's new MSRP.
Microsoft isn't afraid of a clearance sale, which is what they did both when phasing out the old Pros and introducing the Slims, but Sony (and Nintendo, from what I've seen) generally just keep their old models floating around in the channel at normal MSRP, until either they eventually sell or stores do their own cuts to get rid of 'em.







