If you’re an iPhone or iPod Touch user, you may agree with me that this has to be the most useful new usability feature introduced with iTunes version 9, released by Apple yesterday – an easy way to manage and rearrange the order of the apps on your device from within iTunes itself.

The screenshot shows the Sync Applications window in iTunes with my iPhone connected. The large area with icons on the right is exactly what the first home screen on the iPhone looks like.

The small thumbnails you see in the far right-hand vertical column indicate further screens with more apps (I have eight screens with some 89 apps installed). On your iPhone or iPod Touch, you get to those screens by stroking the screen on your device, which shifts them right or left to bring up the one you want.

You then drag around the icons into an order on whichever screen you wish. It’s a painstaking process, one that in my experience demands quite a bit of time and patience.

Until now, the only way you could do this kind of organization was on the device itself – unless you had a jailbroken iPhone and used a third-party program such as Movement (and only if you have a Mac)

So what this means now is all you need is the universally-available and free iTunes 9. No more stroking, touching or poking about on the (relatively small) screen of your device: instead, you do it all on the (relatively large) screen of your desktop or laptop computer using a mouse to drag and drop in a virtual representation of your device within iTunes. All without jailbreaking the device and voiding its warranty.

Incredibly useful and a huge usability improvement.

The only niggle I have is that when I did rearrange apps, removing two, and then applied those changes, iTunes performed a backup of the iPhone which took well over 30 minutes. So this useful feature looks like it’s not something you’d want to do if you’re in a hurry.

Also yesterday, Apple released an updated version 3.1 of the iPhone operating system. One item I noticed in the release notes says “Support for iTunes 9.” So I made sure I installed the OS update on the iPhone before updating iTunes and syncing the device to it.

There’s no guidance that I’ve seen saying you should do things in that order, but it makes sense to me.

In any event, the new iPhone/iPod Touch app management feature in iTunes 9 is very good indeed.

And btw, Apple announced a few other things yesterday. :)