Apple has released the iPhone OS 3.1 Beta 2 to registered iPhone Developers. The first 3.1 firmware beta added a number of new features to the iPhone OS including non-destructive video edits, Voice Control over Bluetooth and a number of other minor improvements.

According to the release documentation there is no major changes for this second beta version, but more information, usually, comes out once people have time to try it out.

However, there is one major change in the second beta and that is it disables unauthorized AT&T iPhone Tethering. Shortly after the first 3.1 beta was released, there were a number of hacks allowing U.S. AT&T iPhone customers to tether their iPhones, this beta seems to kill that functionality. AT&T will officially support tethering later this summer and it will require an additional plan to get the feature.