This website does work and although it is expensive, it does mean you dont have to send your phone off to a shop!
I got both an iphone 4 and an iphone 3gs unlocked and it is as simple as to plug it in to itunes and your signal comes up! which is great! (full imei unlock)
Only problem we had was that it took 12 days not the 48 - 72 hours as stated on website, although when i called to chase our order the phone was answered and the people were always polite!
Id definitely recommend!