Absolutely, although there are different models of the Galaxy S (EU, US and another variant).
My friend got one and I got straight to work Root'ing it to unlock it for him, it took a while and after about 2-3 hours and trying different Root'ing software, then eventually I found one and it literally took about 15-20 seconds and about 2-3 mouse-clicks and I had an unlocked Galaxy S
If one program doesn't work, look for another and eventually you'll find one that will do it for you, good luck!