IBM announced at ISSCC that it has shrunk the PS3's Cell processor to 45nm. The new 45nm chips have a 34% smaller die than the 65nm predecessors and consume 40% less power.
The greatly reduced power budget will cut down on the amount of active cooling required by the console, which in turn will make it cheaper to produce and more reliable (this means fewer warrantied returns). Also affecting Sony's per-unit cost is the reduction in overall die size. A smaller die means a smaller, cheaper package; it also means that yields will be better and that each chip will cost less overall.
All of these chip- and unit-level savings may or may not get passed on to gamers in the form of price cuts any time soon. It all depends on whether Sony wants to boost its margins and show a profit in its gaming unit, or attract new gamers to the console by lowering the price. Eventually, the cost savings will get passed on to users; it's just a question of when.
Speaking of Cell and sales, the presentation suggests that, despite IBM's promise that Cell could see widespread adoption outside of the console realm, Sony is still far and away IBM's main customer of Cell. Specifically, IBM states the following in the paper digest: "To guarantee the proper operation of existing gaming software, the exact cycle-by-cycle machine behavior, including operating frequency, must be preserved."