The just-announced Apple MacBook with 12" screen looks like it would be good for touring if you want a "full" computer. Pricey, though, at $1299. Weighs two pounds and the battery lasts for nine hours (supposedly). New iPad Air is right around a pound, so the Macbook is pretty competitive weight-wise.

Although, I'd never take a $1300 laptop on tour with me. I'd worry about it too much.