I've read a few threads on getting S-Off and it's over my head. Someone said the latest ICS leak allows S-Off. What I don't know/understand if this just allows the ability to S-Off or it does it for you.
Read that getting S-Off would make flashing ROMS easier
Those are separate thing:
ICS leak
s-off
modified h-boot.
S-off is a bit scary, and a few have bricked their phone. s-off took me a lot of time and many tries.
I personally don't like using the custom hboot, as it is just another risk that can brick a phone. the only thing the custom hbooot gives you is the ability to have the phone show locked, yet act as if it is unlocked.
Before you can even attempted s-off you need to be htcdev unlocked, and I think also rooted. it doesnt matter if you are using gb or the ICS leak.