Daring Fireball's John Gruber has added some carefully hedged speculation about the iPad 2 going carbon fiber to the mix:

I could publish things I’m only half-sure about, like the iPad 2 switching from aluminum to a lightweight high-strength carbon fiber body, but I don’t, because I’m only half-sure and I’ve only heard about it from second-hand sources who themselves are unsure about it. And even if I were to off-handedly mention such speculation, I’d do so in a footnote and take pains to emphasize the uncertain nature of the information and the second-hand status of the sources thereof.

He also weighed in on some of the back and forth iPad 2 rumors, saying the hi-res display was never on the table and wagering SD wasn't either, so they couldn't have been "cut".

Given that the glass makes up so much of the weight and the batteries won't be getting lighter any time soon, would switching to carbon fiber really make enough of a difference that Apple would consider it? Or is just the ability to say "the lightest iPad ever" inc