Good question. This big, compared to the first iPad:
We’re not entirely sure about the 1.8x figure provided
by our friend Nils, but taking a look at another photo from the Engadget liveblog
seems to confirms we have three bigger battery packs now built right into the (thinner) iPad.
Apple’s tech specs page says
it’s a “built-in 25-watt-hour rechargeable lithium-polymer battery” with up to 10 hours of usage.