This was the iPhone Dev Team's approach to unlocking Bootloader 4.6.
As noted during the 25C3 talk that the iPhone Dev Team members gave, this exploit was actually never fixed in X-Gold 608 baseband 01.45.00, only in the next rev, so they were able to use it as an injection vector for some of the earlier hacks that they did on the X-Gold 608 (downgrading the baseband version to 01.43.00, backing up their seczone, etc.)
This relied on a buffer overflow in the STK. The command AT+CSIM=XX caused an overflow that allowed the injection of an unlock exploit without jailbreaking
Leaked Source[edit source]
Zibri removed it from the Google Code page, but the source is still easily available via google cache, or the fact that Google Code wiki pages are svn based and you can easily just look at an earlier rev :)
On the page before the source got deleted, Zibri referred to it as C source, although by the looks of it he may have failed to realize that it is a payload meant to be run off of a TurboSIM