Also, that's a Kindle DX she has in her hand, not a Kindle 2. Everyone else on the Heroes set needs to stand on apple boxes to hide the fact that she's six-foot seven.
Of course, she doesn't actually use this to memorize her lines. For that, she has a little midget inside her ear to repeat them back for her in real time. I wonder what she's reading. [Egotastic - Thanks Travis!]
Ed. note: That bit about the DX, that was a joke, having to do with Hayden P.'s minuscule size. You know? Oh, nevermind.