The iPhone 3G is indeed an amazing phone, unfortunately it is not available to all even in countries where it is sold. Come August 20th, that will change for many, for that is when USB fever will be releasing their iPhone 3G unlocking tool.
You can now pre-order the .10mm thin piece of FPC that you connect to your SIM card. *Although* using this does requiring snipping one corner or the SIM card, so if something goes wrong.. its over. This very useful tool will cost you 35$. Enjoy!