So I was running 1.1.2OTB with a TurboSIM...
I decided to restore because I wanted to ensure all the stuff I had done to enable that was removed.
Previously I was running on iTunes 7.5 with updates disabled.
Restore via iTunes 7.6.1 went fine and then I quitted and ran iJailbreak 0.53 and chose 'unlock' - I put the AT&T SIM in just to be sure
Seemed to be going OK but in fact it hung with the "jailbreaking & unlocking" message on the app and the 'connect to iTunes' icon on the iPhone. I gave it 15 minutes, still nothing.
I then force-quitted the app and pressed the power button on the iPhone - it then proceeded on the iPhone screen to run through a load of command-line stuff about deleting, unable to delete, fixing, writing etc.
After that the iPhone rebooted and appears to be unlocked! Not exactly what I expected but seems to be OK
Installer app is present
Now I need to add my contacts etc., music and all that, I'll post later on the outcome.
So far so good...