This has become a little bit of an issue for us, too--it's been so interesting reading everyone's responses! Nice to hear other ideas and perspectives.
My dd10 is slender (about 4'7'' and not quite 60 pounds). She's going into
5th grade, and this past year in school, the kids learned all about puberty (yes, ALL about it

). Dd started using deodorant this year after convincing me that most girls in her class used it (I asked several parents, and my dd was correct)--she didn't need it. She also doesn't need a bra and is very thankful, as she hates the feel of anything around her chest. I've even had to cut the bra-like things out of tank tops for her!
I have told my dd that she's too young to shave her legs, and she's accepted that, but now, after reading all these posts, I'm re-thinking. She does have quite hairy legs (always has), and if she's asking, then maybe she's self-conscious...
Also, about the AG book...dd had no interest in it a year ago--thought it was "gross!" Now, however, she's fascinated and has poured over it. Sigh. Guess my baby's growing up!