PS3 Slim would not only be smaller (33% according to Sony; it's slim!), but use less power (34% less), weigh less (36% lighter), and cost less (a solid Benjamin!) all pointed to one thing: black magic.
Turns out, our hunch was wrong (at least in part). IBM has revealed that the Cell processor under the newly matte-ified hood of the PS3 Slim was "manufactured using an advanced 45-nanometer manufacturing process" that will deliver "many performance improvements while drawing less power than earlier chips." Of course, smaller chips are cheaper to produce and would, at least in part, contribute to the Slim's slimmer pricetag. There's no word on any size or cost reductions for the PS3's Nvidia-built RSX graphics chip; however, historically, it has lagged behind reductions in the CPU.
In addition to IBM's claim of "performance improvements" IDG News Service reports that the Slim "adds hardware enhancements that make it speedier" though, curiously, Sony never mentioned any performance improvements coming with the Slim. Since gaming consoles are engineered to a specification – so developers aren't programming for a moving target – we're thoroughly skeptical of of any user-facing performance improvements. Lucky for us, we've got a Slim at our disposal, so we'll throw some fire at it and see how it responds.