Once you update your iTunes to version 9 and your iPhone to version 3.1. you will see a lot of changes. Some will say, "No big deal," others will say, "My life is saved!"
The Shopping Cart becomes My Wish List, new look for the iTunes store, Home Sharing your media to all in local network, Classical Music treated as one (finally!), syncing is now much more flexible and powerful, for more details: Apple's iTunes A to Z
The feature that I like, maybe more than any in this early review is the ability to Organize Your Home Screens. In the past, when you connected your iPhone to iTunes on your computer the Applications tab was a bit of backwater. Little control and I have to say it seemed that the settings ignored your commands.
Now you have almost complete control. On the left is a scrolling column of all your purchased apps in which you can enable and disable each app for syncing to the iPhone. Not dissimilar to the old method except that now you see an icon for each and the ability to sort by name, category and date. There is Search window as well.
But the real fun and power is in the column on the left. Here you see a representation of each of the iPhone's screen pages where you can arrange the apps on the screen. Yes that is correct, you are arranging your iPhone apps in ITunes on your computer, no more funny fussing with the shaking apps on your iPhone.
I have but one remaining complaint, I would like to delete the default Apples apps i do not like or have a better version: stocks and weather come to mind. Oh well, must leave something for later upgrades.