This is a data toggle for SBSettings. The internal EDGE toggle does not work on 3.0 in many cases. This toggle will kill data properly. It does so by setting an IP address of 1.1.1.0 for the data adapter.
While this will work on 2.x iPhones, it is not needed. The internal EDGE toggle works just fine on 2.x devices and is much faster.
Note: when this toggle is disabled, your 3G and/or EDGE toggles may still show enabled. It is recommended to disable EDGE toggle in SBSettings and stop using it.
Further, when reenabling this toggle, the iPhone may freeze up for up to 15 seconds as commcenter is being reloaded. You will also lose connection to and reconnect to your carrier during this time.