Unlocked version of iPhone 4 is now available for selling at the Apple Store for $649 on 16gb models and $749 on 32gb models in the US. This is intended for iPhone users who are frequently going in and out of the country with no access to AT&T (GSM) but still want to use their iPhones.
This could be the start of unlocked versions of iPhone all over the world via authorized retail outlets. We don't have a word yet but we are hopeful that this will happen. If in case, unlocked versions also reach Philippines, then we don't need those very expensive gray market unit sellers anymore, including the unlocking services being offered by unauthorized service/jailbreaking centers or guys.
Only the GSM version is being sold with unlocked option.
From Apple Store