IPhone :: ITunes Still Transfer Contacts To MicroSIM?

Probably a dumb question, but I've never fully understood the purpose of a SIM card with the iPhone when iTunes supposedly syncs all contacts and phonebook entries anyway.But I believe I have my contacts stored on my sim card and I always do regular backups with 'contacts' checked in iTunes, so am I safe when the new phone comes out with the microsim? Will iTunes automatically sync all my contacts back onto the phone from my 3.1.3 firmware?And how do you get your contacts back onto the new SIM? AFAIK you can't manually put contacts onto the SIM through iPhone unless it's jailbroken.