Just my simple post to report my experience with iPhone 3G by Vodafone IT.
It is OTB unlocked by default to any carrier/SIM.
I tried with TIM IT and H3G IT SIM too.
All SIMs are accepted without any issues... GOOD!
Then go to jailbreak the 3G with PwnageTool 188.8.131.52: ALL FINE!
No need to activate by PwnageTool because the baseband accept any SIM.
The iPhone 3G is working now with H3G SIM and it's jailbroken
There are some people that was confused and in doubt about the working couple iPhone 3G ITA version and H3G IT SIM.
I can confirm: they work fine together