it shouldn't be unlocking but activating.  i bought 2 8gb iphones at Telstra (aus) and they had to activate the phone afterwhich i called a number to unlock the phone.  i had to use itunes to restore the iphone to ensure it is unlocked.

unlocked will be able to use with any telcos.  NZ phones aren't locked in the first instance so there's no need to unlock.

Australia iphones are locked to the telco which sells them.

Say if you buy from Optus, it will be locked to Optus.  If you buy from Telstra, it will be locked to Telstra.

You will have to activate the iphone before it can be used.  This is different from unlocking.  Spring activated the iphone himself using iTunes.  Some people do it at home but most of them had their phones activated at the store.

You have to request for the telco to unlock the phone and pay the unlocking fee.  Different telco different prices.  Then the telco will ask Apple to unlock the iphones by the imei.  You got to check on your own using iTunes to see if the iphone is unlock.  You have to do a restore in order to know that the phone has been unlocked.  *this part you can ask the telco how to do it or you can google for the procedures*

If you are interested, I can set up a simple guide, but not now cos I'm flying off tonite.

and NO, you cannot unlock the iphone yourself yet.

@zijian,
Yes if Ur planning to get a phone from Australia the best deal would be the Optus prepaid one.  If I'm not mistaken, the 16GB will cost U AUD925 - make sure ur friend get Optus to UNLOCK the phone before he brings it back.