Segundo o George Hotz, ainda não... http://iphonejtag.blogspot.com/2008/07/iphone-3g-unlocked.html
"The possiblity of unlocking, which is very distinct from jailbreaking, is based entirely on the baseband bootloader. Apple doesn't appear to upgrade the bootloader on phones in the field, probably for fear of breaks. So any old iPhones out there today, regardless of version, can be unlocked.
The iPhone 3G uses a different bootloader, which I believe there aren't any known exploits in yet. So no unlock."
EDIT: Mas ao mesmo tempo, ele faz um aviso ao Dev Team (a outra equipa que trabalha no desbloqueio / "jailbreaking") do iPhone, que o yiPhone vem aí...