Apple recently released iPhone OS 3.1 beta firmware and SDK to developers. Unless you’re a developer I recommend you to not download this firmware and wait for the final 3.1 firmware to be released. Apple hasn’t announced when iPhone OS 3.1 will be released, but I will make a post here notifying you once it’s out!

Here are some new features that have been discovered in iPhone OS 3.1 beta so far:

The baseband has been updated to 5.08.01 – ultrasn0w users should not use the iPhone OS 3.1 beta, otherwise their iPhones could be permanently locked!
iPhone 3GS – When you’re trimming your videos you now have the option of saving the original video by tapping the “Save as copy” button.
Voice Control is finally working over bluetooth now!
When you move your icons around the iPhone vibrates
MMS is enabled by default but does not work for AT&T users
The AT&T profile is updated to 4.2
Improvements to OpenGL and Quartz
There’s now a VideoEditorController API – Allows third party apps to call up video editing UI
Video picker API
I’ll update this post as more features are discovered!