Is Hong Kong the first market in the world to get an iPhone 3G which is both officially unlocked at the time of purchase and not tied to a carrier plan? According to the Apple HK iPhone store page, quite possibly:
iPhone 3G purchased at the Apple Online Store can be activated with any wireless carrier. Simply insert the SIM from your current phone into iPhone 3G and connect to iTunes 8 to complete activation.
They’re not cheap though. The 8GB phone costs HK$5400 (approx US$700) and the 16GB is HK$6200 (approx US$800).