One of the nicest additions is the ability to remotely lock your iPhone if you're a MobileMe subscriber. It could be very helpful if you've left it somewhere and are not sure where, or you know it's stolen but don't want to wipe all your content in case the phone is quickly recovered. This doesn't replace the very welcome remote wipe feature, but it is a nice add-on.
The place to activate the remote lock is on your MobileMe settings page, which you can access from a web browser. You can give a four digit code, and if your phone is turned on it will immediately lock. You will also get a confirmation e-mail from Apple.
One item to note, once you have done this, it is not a one-time thing. When you get your phone back and you unlock it, it will lock up again when your auto-lock activates unless you turn the feature off in your iPhone settings. I tested the remote lock function, and it worked as advertised.
Another worthwhile addition in the iPhone 3.1 software is the ability, finally, to use Bluetooth voice commands with a Bluetooth headset. This feature should have been included in the iPhone 3.0 software, but I am glad to see Apple address this obvious shortcoming,
With my Jabra Bluetooth headset I could initiate a voice call without any problem. I also asked the phone what song is playing and got the correct answer, but the voice responded through the phone and not the headset. No big thing.
It's nice to see Apple cleaning up some of these little issues as the iPhone moves forward. Wonder where it will be in a year?