Silverthorne is a teeny processor built on the 45nm process (like the much-ballyhooed Penryn), designed for UMPCs, subnotebooks, mystery Apple products and any other smallish gadget that needs real crunching on an ultra-lean power diet.
It's about as powerful as the first Pentium M chips (Banias), but while those idled at 5W and averaged 24.5W, this little guy sips as little as 0.1W in its idle state, with peaks up to just 2W on the 2GHz model. It's really cheap to pump out too, tapped for the $200 OLPC at one point.
It comes in a couple different flavors up to that 2GHz version. To get athletic performance—it's a full-fledged x86 chip, not a half-baked cutdown—out of an anorexic processor, Intel worked all kinds of design mojo, like a new quick-wake deep sleep state. It's still a bit too hungry for smartphones, though. So, while it's a neat piece of silicon, as Ars says, it's still got a ways to go, especfially with stiff competition from ARM and TI. But that's a good thing.