Apple has seeded developers of their iPhone Developer Program with the third beta version of iPhone OS 3.1 (Build 7C116a). Apple also released a new version of the iPhone SDK 3.1, Beta 3 (Build 9M2808).

The download size is 307MB. Apple hasn’t provided details about the improvements expected in the third beta version of iPhone OS 3.1.

It is expected that Apple will allow developers access to the tools they need to produce augmented reality iPhone apps with iPhone OS 3.1.The second beta version of iPhone OS 3.1 broke the hack which allowed users to enable tethering in the US and other countries where the feature is not officially available.

The first beta version of iPhone OS 3.1 had revealed the following changes:

Non-destructive video editing means trimming a clip no longer saves over the original video but gives you the option to “Save as copy…”
Voice Control now works over Bluetooth
iPhone vibrates when moving icons
Updated AT&T profile to 4.2
Updated modem firmware to 5.08.01
Improvements to OpenGL and Quartz.
APIs to allow third party apps to access videos and edit them.
“Fraud Protection” toggle is now available in iPhone Safari settings.
iPhone startup and shutdown and iPhone apps launch is faster in iPhone OS 3.1.

If you are enjoying the tethering functionality using the hack then please do not update your iPhone with iPhone OS 3.1 when it is released.

The iPhone Dev team has also warned users who are interested in unlocking their iPhone 3G or iPhone 3GS should avoid updating their iPhone with iPhone OS 3.1 (including iPhone OS 3.1 beta) until they release tools to update firmware without updating the baseband. They have also clarified that the warning does not apply to first generation iPhone users as it uses BootNeuter for the unlock, not Ultrasn0w.

We will let you know if the latest beta version of iPhone OS 3.1 reveals any more changes so stay tuned here at iPhone Hacks.