In case you are living under rocks, you may don't know that Ultrasn0w carrier unlock will be updated tomorrow (this Sunday) to provide a full unlock for iPhone 3GS / 3G on baseband 05.15.04 and lower ones. Anyway, iPhone 4 unlockers will have to wait a bit longer but we have good news for you too.

iPhone hacker Sherif Hashim is doing a great progress in unlocking iPhone 4 baseband 02.10.04 on iOS 4.2.1 / iOS 4.1 since he, according to this tweet, has provided very nice crashes for iPhone 4 baseband, also the iPhone Dev Team will start exploring more starting from this Monday.
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Faiz: @MuscleNerd btw @sherif_hashim was working on i4 since long ? Did he not find anything interesting.

MuscleNerd: @mfaizulislam just the opposite Click here to enlarge @sherif_hashim has provided very nice crashes for i4 BB, which we can explore more starting Monday Click here to enlarge
This news gives some hope to iPhone 4 users who stuck on iOS 4.2.1 or iOS 4.1 with upgraded baseband as BB 02.10.04 or BB 03.10.01. More updates as they come! Stay tuned !Click here to enlarge