With the release of the 188.8.131.52 ROM however, the unlock system works properly (i've just tested it)!
The downside is that applying the official update blats all your data, overwrites your recovery etc. etc., so i've repacked it in an update zip below which only flashes boot, system and the updated radio.
So if you want to unlock: Nandroid backup, flash this zip, boot, unlock, Nandroid restore. Done!
DOWNLOAD (MediaFire Pro)
PS I used these guys for me code (nice fast delivery - http://shop.ebay.co....t_international