Windows Phone powered Samsung ATIV S is getting a firmware update
The update is scheduled to hit your Samsung ATIV S sometime before the calendar turns to June. There are only a few days left in this month, so you should expect the update to reach you shortly. After the update, both unlocked and carrier branded versions of the phone will offer the same features. The former did not come with the ability to run Wi-Fi tethering.
source: WindowsPhoneItaly (translated) via WPCentral