There was a report last night that the iPhone 3G sold by the carrier, Three, in Hong Kong is unlocked; meaning it is not tied to a specific carrier. This news was a bit hard to believe as news from other countries like US, Japan, Australia and New Zealand, the iPhone 3G sold there are all locked to the respective mobile carriers.
Therefor, if you do not want to stick with Three's service you now have a choice, but the cheapest choice is:
HKD4680.00 + HKD188 x 24 months + MTR Fee (HKD12 x 24) = HKD9480.00 - HKD1742 = HKD7738 (including the rebate you will receive over 2 years)
Now I have first hand confirmation from a friend who purchased one of these iPhone 3G at Three HK. He was able to put in a PCCW SIM card while having full access to all functionalities of the phone including EDGE and GPRS functions.
Is this really worth it. I say not, especially if you already have an iPhone (1st generation). Wait for the other carriers in Hong Kong; namely PCCW and/or Smartone-Vodafone receive the rights to sell the iPhone 3G.