It's quite interesting reading about how an iPad affected a whole family's computer usage. I've been playing with a little Acer Aspire Revo R3610 (the dual-core Atom processor with 2Gb RAM) that I've installed Win 7 on. I've got two monitors hooked up to it (via VGA and HDMI ports) and for what I seem to spend more of my computer time doing (surfing, emailing, word processing) it seems to be coping perfectly (the reason for trying it is it uses 25W at max power, while my Pro run at 180-200W under any load).
So while we seem to be continually marching on when it comes to more cores and faster clock speeds, do we need them? For most people, who use their computers as I do 99% of the time, the extra power is unnecessary.
What we could do with is driving forward the reduction in heat (to help make machines quiet) and power reduction (so they can run longer on batteries or be left on permanently for little cost).
For me, the benefits of having something that is either on 24/7 or boots in less than five seconds outweigh the extra power. It means I can quickly check email or look something up nearly instantly, rather than waiting for an over-powered machine to grind into life. Imagine a machine that can run most of the apps you want and draws less than 10W (there are some but they're pricey), you may as well leave it on permanently.
This dichotomy has already started to show in the chip world, the Atom only really exists to serve things like netbooks. Over the next few years though, the biggest we'll see will be in the mobile and low-power desktop chips, the big boys will just stay on their current paths of more cores.