I've just been trying out the audio book given us in our lucky bags at the National Year of Reading conference last week. I love the three speeds. The reader's words are magically squidged up so that she speaks faster or slower but at the same pitch, without the squeaky helium effect.
Jean Gralley has sent me this link to another flash animation of hers about the digital possibilities for picture books: http://jeangralley.com/books_unbound/
I'm still loving reading on my Sony Reader, still haven't purchased a book for it and am pondering how different it feels to own an object which sits on my shelf as opposed to buying a download which I then inject into my brain through reading. The book becomes an experience rather than an object - which seems quite healthy to me.