DO NOT Upgrade To iPhone FW 3.1 ( Including Betas )

So, Apple finally released iPhone FW 3.1 Beta 1(build: 7C97d) for developers with the following list of changes:

Increase the speed of Boot (timing of ignition decreased)
Several changes AudioToolBox the OpenGL | ES, the Quartz Core, the IO Kit (editor of images and video.) Soon we will see how they affect applications.
Added the new option “Save and Copy” while editing the video. In Firmware 3.0 when a video is cut completely you will loose the original file and it will be saved only one remained unchanged. Now it is possible to maintain both, so we can send short video via MMS without loosing the entire video.
If you hold down the Springboard icon, it will not only just start shaking, but the iPhone will emit a small vibration
Solved the problem of multiple SMS
Better network reception
Improved WiFi Reception
Voice Control also works with Bluetooth
The modem version is updated to 5.08.01 (this one is in bold, read below )
Added new API that allow developers to access and edit the video, which will arrive soon in AppStore applications to edit video, add effects, frames and more.

The new Firmware 3.1 (already starting from beta) updates the phone’s modem version 5:08:01 and this prevents the use of Ultrasn0w the DevTeam software used to unlock the phone for 3G purchased abroad.