iPhone Dev Team had released PwnageTool and Redsn0w that allowed users to update their iPhone 3G or iPhone 3GS’s baseband to 06.15.00 along with Ultrasn0w 1.2 to unlock it few days back.

Some users have reported significant loss of GPS signal after upgrading to baseband 06.15.00. iPhone Dev team has also confirmed that though baseband 06.15.00 is capable of GPS, it might require further hacks.iPhone Dev Team has published the following update on their blog:

Unlockers have been reporting mixed results about GPS functionality at 06.15.00.

Until we can track down what differentiates those who retain GPS vs. those who lose it, be conservative and assume you’ll lose GPS at 06.15.00.

As we work on finding the cause (and possibly a fix), please report your personal findings in our comments section.

(Update: early indications are that while 06.15.00 is capable of GPS, it will require some further hacks. But please still be conservative and assume you will lose GPS at 06.15, in case the hacks don’t work).

So if you are planning to unlock your iPhone then please proceed with caution as you might end up losing GPS on your iPhone.

If you have successfully unlocked your iPhone using the combination of PwnageTool or Redsn0w and Ultrasn0w then please let us know if you are experiencing any issues with GPS on your iPhone in the comments section below.