The dual-SKU strategy is also a fairly clever way to phase between two different models of the console. They need to bring in the 80 gig model for the reasons already stated, but they can't put them on the shelves at the same time and at the same price as the 60 gig. They also needed a price drop -- so, they combine the two moves, dropping the price while reducing their losses by selling the 80 gig (which is actually significantly cheaper to produce) as a "premium" model. Eventually the 60 gigs are all sold off, and the 80 gig replaces it as the sole SKU (presumably at the lower price).
Microsoft is doing a much clumsier job of transitioning between models. Some of the 360 Premiums on the shelves right now have an HDMI port and a cooler chipset, while the older ones being sold next to them for the same price don't. This is a sure-fire way to annoy customers, but considering MS has already got 4 different SKUs in stores, it isn't exactly practical to add another.
Besides, hasn't Sony already come out and said that the 60GB's are gone?
What makes you say that? I believe Sony has actually come out and said they intend to pursue a single bundle strategy for the forseeable future after the 60 gigs are gone; and while I'm not inclined to accept what they tell us at face value, I don't see anything indicating they're "set" on this strategy. Like I said before, it looks to me more like a temporary strategic move.
And Sony has said the 60 gigs are shipped, but as they and Microsoft have shown us this past year, that's a far cry from "gone." There are probably still at least a million units sitting on store shelves, and those likely won't be sold until mid-way through the holiday season.
