How Do I Find My Iphone 3g Cell Phone Number From A Purchase I Made Online Yesterday

I just purchased an iPhone 3G at the at&t wireless store online (with a contract). I selected the plan already so when it comes in it should be ready to go after I connect it to iTunes. Anyway, it hasn't arrived yet, so I was wondering if there was some way to figure out what my new number was. Also, when it does arrive, will it tell me what my cell phone number is (if so, than where?)