Thanks to Laurel for sending me part of an interview with HP3 director Alphonso Cuaron that was posted on MoviePoopShoot.com:
I asked whether growth and hormonal development issues will be affecting the appearances of Harry (Daniel Radcliffe), Ronald (Rupert Grint) and Hermione (Emma Watson). No, he said -- the really big changes will be evident in the Potter flick after Azkaban. Grint, he acknowledged, has grown the most of the trio, and Emma is getting slightly breasty and acting more and more precociously teenaged. I don't know about this. In the one-sheet for the current Harry Potter, Radcliffe looks like a 29 year-old attorney.