No, that's not typical. You will want to ask his pediatrician about this - 9 years old is about the earliest age for onset of puberty in boys that's considered typical.
Oops, forgot to include the link! Description of "partial" precocious puberty, if he's showing no other signs than just pubic hair.
http://kidshealth.org/parent/medical/sexual/precocious.html
First of all he is entering puberty, it may or may not be precocious puberty, if it is threre is nothing you can do about it anyways.
I have to tell you it is weird your still seeing him nude, he is 7 and should be showing some standard of modesty by now. Hopefully your not still bathing a 7 yr old? You can search the subject mate, going to a doctor sound pretty lame to me.