That's a 6x larger battery, and it most likely scores only 3x faster in browser tests (this dual core A15 can score under 700 ms in Sunspider). And that's disregarding the much lower price and weight of this machine.

X2xx seem to be nice laptops; i'm afraid to buy one though because I had quite bad experience with intel laptops including my 2009 and 2010 macbook pro's; they just conk out after 3 hours with new batteries. And I check often to see what is running and work almost only in the terminal (must say, since i replaced the native terminal of mac os x with iterm3 http://www.iterm2.com/ it is much better). The other intel laptops I had didn't even (ever) make that (even the ones with tiny screens). And I don't buy the cheapest stuff.

On the other hand; my S2, iPad 1, Pandora and Zaurus easily make 10 hours. I don't spare them from hard work but they do much better. On the Pandora & Zaurus I can work normally mostly (despite the tiny screens), so I don't mind a 10 inch screen (but preferably with an insane high res like the Nexus 10) at all.

Recap: X220 idling: 8.5W. iPad's max 5W.

Agreed about one thing, Intel is finally starting to care about power efficiency. The CPUs have been solid since the Pentium M days, but the chipsets feel more neglected.