All iPhone developers that are officially registered in the iPhone Developer Program were seeded the new iPhone OS 3.1 beta 3 version firmware. The firmware, labeled 7C1161, came in at a hefty 307MB. The new beta release is rumored to allow augmented reality apps (iPhone applications which mix real-world objects with digital data) to function.
The first beta release of iPhone 3.1 updated the bluetooth and video feature of the 3.0 firmware. Beta 1 users were able to invoke voice control with a bluetooth headset rather than just a wired headset or native iPhone microphone. Developers are also able to save copies of a trimmed video, rather than losing the cut-pieces entirely.
The second beta release of iPhone 3.1 allowed developers to connect to a system wirelessly, rather than having to connect a USB cord.
The third beta release of iPhone 3.1, which came out today, must be downloaded by developers before midnight tonight if the developer wants to continue using the device without interruption. While the details of "what exactly is in there" aren't clear yet, it seems that the 3.1 beta update has something to do with all those amazing augmented reality apps we've been seeing.
The 3.1 update should be available in September.