HERE IS A WARNING FOR ALL IPHONE USERS
The previous quote was taken directly from Hackint0sh.org
UPDATE: Bootloader 3.8 and earlier bootloader versions (aka 3.1) are present in many different iPhone software 1.1.1 and 1.0.0 (1.0.2 or 1.0.1 still unknown). The bootloaders are present in the stock IPSW files and vary according to seed. Here is some proof:
UPDATE 2: It seems a variant of JerrySIM from Project Jerry [which was being developed by the Dev-Team] can 'cure' the problem. However, that is only if the Dev-Team decide to finish developing Jerry and releasing it.
UPDATE 3: It has become clear that the firmware culprits [where Bootloader 3.08 and 3.01 are found] were firmware 1.1.1 and 1.0.0. It has been generally accepted and believed that 1.0.2 is clear of these freak bootloaders but it is not 100% clear, yet.
So to help clear things up, here is a small explaination. Right now there are 5 different Bootloaders, [yes you read right 5]. These are:
1. Bootloader 3.09
2. Bootloader 4.06
3. Bootloader 3.09 Fakeblank
4. Bootloader 3.08 Recent appearance
5. Bootloader 3.01 Just Appeared
Now, I'll explain a bit more on these different bootloaders.
I. Bootloader 3.09 was the first bootloader to be used on iPhones that were made on week 45 or earlier in 2007. This Bootloader [3.09] allows the iPhone SimFree (IPSF) paid unlock aswell as GeHot's IPSF-like free unlock. Also, this bootloader allows you to downgrade your Baseband (which controls your Wi-Fi, EDGE and Calls) firmware. Downgrading baseband firmware is useful when you updated by mistake or/and want to go back down to a previous iPhone firmware. Bootloader 3.09 does not allow the bootloader to update.
II. Bootloader 4.06 is the current bootloader being flashed on iPhones as of Week 45 or later iPhones of 2007 and all 2008 iPhones. This bootloader does not allow your baseband to be downgraded, so once you updated, you are stuck there. Also, this bootloader does not allow the IPSF unlock. As you may remember this bootloader caused many problems when it was reviewed by the Dev-Team to look for a software unlock. Now, thanks to GeoHot, this bootloader [4.06] can be unlocked. One important exploit in this bootloader is that it can allow you to downgrade [software and hardware wise] itself to the earlier 3.09 or even the modified Bootloader 3.09 FakeBlank, which is good if you want to downgrade baseband or apply an IPSF-like unlock.
III. Bootloader 3.09 Fakeblank (BL 3.09FB) is a modified bootloader created by Geohot and the Dev-Team. It has all the capabilites bootloader 3.09 has, but has one exception. This bootloader, since it's modified, can allow you to upgrade back to bootloader 4.6, meaning its 100% reversible. One big flaw of it, is that if you downgrade to firmware to 1.1.1 or earlier, the bootloader seems to disappear and a new bootloader appears (more on that next) because it is mis-read by iTunes.
IV. Bootloader 3.08 is very, very new. This bootloader is a mistake made by iTunes when installing/flashing firmware 1.1.1 or earlier on a BL 3.09FB. It is thought that this happens because BL 3.09FB is read as nothing (in other words no bootloader present, even though there is one) by iTunes when restoring the stock firmwares; hence, iTunes flashes a new bootloader. Since its [bootloader] new, not many information is known, but here are some things. The strongest suggestion is not to downgrade to 1.1.1 or earlier when using BL 3.09FB untill the mistake is corrected. The greatest worry of this Bootloader is the fact it has all the exploits of 3.9, which means no bootloader upgrade. After this info, not much is really known of bootloader 3.08.
V. Bootloader 3.01 is the most recent bootloader. It is present in the stock IPSW for 1.1.1 and 1.0.0. No other info is known at this time
The previous quote was taken directly from Hackint0sh.org
UPDATE: Bootloader 3.8 and earlier bootloader versions (aka 3.1) are present in many different iPhone software 1.1.1 and 1.0.0 (1.0.2 or 1.0.1 still unknown). The bootloaders are present in the stock IPSW files and vary according to seed. Here is some proof:
UPDATE 2: It seems a variant of JerrySIM from Project Jerry [which was being developed by the Dev-Team] can 'cure' the problem. However, that is only if the Dev-Team decide to finish developing Jerry and releasing it.
UPDATE 3: It has become clear that the firmware culprits [where Bootloader 3.08 and 3.01 are found] were firmware 1.1.1 and 1.0.0. It has been generally accepted and believed that 1.0.2 is clear of these freak bootloaders but it is not 100% clear, yet.
So to help clear things up, here is a small explaination. Right now there are 5 different Bootloaders, [yes you read right 5]. These are:
1. Bootloader 3.09
2. Bootloader 4.06
3. Bootloader 3.09 Fakeblank
4. Bootloader 3.08 Recent appearance
5. Bootloader 3.01 Just Appeared
Now, I'll explain a bit more on these different bootloaders.
I. Bootloader 3.09 was the first bootloader to be used on iPhones that were made on week 45 or earlier in 2007. This Bootloader [3.09] allows the iPhone SimFree (IPSF) paid unlock aswell as GeHot's IPSF-like free unlock. Also, this bootloader allows you to downgrade your Baseband (which controls your Wi-Fi, EDGE and Calls) firmware. Downgrading baseband firmware is useful when you updated by mistake or/and want to go back down to a previous iPhone firmware. Bootloader 3.09 does not allow the bootloader to update.
II. Bootloader 4.06 is the current bootloader being flashed on iPhones as of Week 45 or later iPhones of 2007 and all 2008 iPhones. This bootloader does not allow your baseband to be downgraded, so once you updated, you are stuck there. Also, this bootloader does not allow the IPSF unlock. As you may remember this bootloader caused many problems when it was reviewed by the Dev-Team to look for a software unlock. Now, thanks to GeoHot, this bootloader [4.06] can be unlocked. One important exploit in this bootloader is that it can allow you to downgrade [software and hardware wise] itself to the earlier 3.09 or even the modified Bootloader 3.09 FakeBlank, which is good if you want to downgrade baseband or apply an IPSF-like unlock.
III. Bootloader 3.09 Fakeblank (BL 3.09FB) is a modified bootloader created by Geohot and the Dev-Team. It has all the capabilites bootloader 3.09 has, but has one exception. This bootloader, since it's modified, can allow you to upgrade back to bootloader 4.6, meaning its 100% reversible. One big flaw of it, is that if you downgrade to firmware to 1.1.1 or earlier, the bootloader seems to disappear and a new bootloader appears (more on that next) because it is mis-read by iTunes.
IV. Bootloader 3.08 is very, very new. This bootloader is a mistake made by iTunes when installing/flashing firmware 1.1.1 or earlier on a BL 3.09FB. It is thought that this happens because BL 3.09FB is read as nothing (in other words no bootloader present, even though there is one) by iTunes when restoring the stock firmwares; hence, iTunes flashes a new bootloader. Since its [bootloader] new, not many information is known, but here are some things. The strongest suggestion is not to downgrade to 1.1.1 or earlier when using BL 3.09FB untill the mistake is corrected. The greatest worry of this Bootloader is the fact it has all the exploits of 3.9, which means no bootloader upgrade. After this info, not much is really known of bootloader 3.08.
V. Bootloader 3.01 is the most recent bootloader. It is present in the stock IPSW for 1.1.1 and 1.0.0. No other info is known at this time