TWRoO on 24 March 2009
They were waiting until they could actually build some stock of the old ones before changing over I suppose.
I don't really know anything about chipsets but I would guess it takes at least some time to change to a smaller die, which would mean temporarily lowering production of the old ones to introduce the new? Thus super-high demand stopped them changing.
As for the no fan thing...that is pretty impressive, but then they did spend research and development time making their chips small and cool rather than big, hot and technologically advanced like Sony and MS.
