Beta 1
Improved Wi-Fi
Faster boot up time and various speed improvements
Provides vibration feedback when home screen icons jiggle to indicate they're ready to be moved or rearranged.
Trimming video clips on the iPhone 3GS now offers the ability to save the edited version as a copy rather than simply overwriting the original file
Some reports of MMS being activated on U.S. models, but it seems to stall before actually being sent out over AT&T's network (most likely because of the MMS opt-out currently active on most AT&T iPhone texting plans)
Safari now has a toggle for "Fraud Protection" under its Settings pane
Bulgarian keyboard is in the BDS layout, not QWERTY layout
On iPod Touch 2G the Voice Memos app now successfully records audio if you plug your microphone after you have started the application
Voice Control over Bluetooth is now available, allowing users to Initiate calls and control music playback via Bluetooth headsets (however, voice control while plugged in to car audio systems no longer works)
It is reported that the version 3.1 improves battery life on the iPhone 3GS[citation needed]
Updates the "Carrier" profile for U.S. users to "AT&T 4.2" as opposed to "AT&T 4.0"
Improves reception
iTunes Store icons rearrange themselves back to default after opening and closing the app
Developer Extras
Improvements to OpenGL and Quartz
API's allow third party apps to access videos and edit them
Gives programmers their choice of video recording quality
A pair of new app interface classes that are known to relate to graphics, but which haven't had their functions identified
Calendar event alerts will be shown also with a pop-up, much like push notifications
Xcode 3.1.3 has also been released and is said by people aware of the update to improve facilities for creating a new project as well as setting a target configuration.[citation needed]
Beta 2
Enables connectivity to devices for developmental purposes wirelessly instead of requiring tethering via the dock connector
New accessibility options including VoiceOver and high contrast mode can be toggled with three clicks on the home button, as well as new video saving and editing buttons.
Updates the "Carrier" profile for U.S. users to "AT&T 4.5"
Beta 3
Ability to copy and paste full quality videos from camera into email
Under usage tab in settings able to view data sent and received over tethering
Instruments over Wi-Fi
New Enhancements to Core Audio in iPhone
Failover support for HTTP live streaming
Developers reporting removal of vibration feedback when putting icons into rearrange mode
http://en.wikipedia.org/wiki/IPhone_OS_version_history