First up are some of the basics: there has been a simple change to the iTunes
This should offer a good overview of just how much the iTunes UI has been updated and polished, though impressively without any major or unsettling changes. Dan Lurie noted that it all has a very 'web 2.0-ish' feel, and I tend to agree. Since the iPod was a major player in today's events as well, I figure changes to the iTunes + iPod relationship are as good a place to start as any.
Managing your iPod just became a whole lot easier
You can see what Mr. Jobs meant when he said you can now interact with and configure the iPod right from within the iTunes interface, instead of having to clunk around in the preferences. Underneath the display panel at the top of iTunes are now a series of tabs when an iPod is selected, offering the familiar options of choosing whether to sync the iPod, which podcasts to sync, etc.
TV show syncing now has its own configuration options, including '5 most recent' and '5 most recent unwatched.' I'm sure these will be welcome options to those chronically addicted to more than a few iTunes TV shows.
Also at the bottom of the iPod panel is a much-improved space meter that delineates between music (blue), video (purple), 'other' (orange - I guess this is any files/folders and possibly photos you have on the iPod) and, of course, free space (white). In an interesting change to Apple's fundamental UI behavior, they have added dedicated 'Cancel' and 'Apply' buttons in the bottom right of the iPod configuration panel, allowing users that last minute chance to decide whether they really want to commit a change.
New ways to view your library
The new viewing options for the individual library entries in the Sources list (Music, Movies, TV Shows, Podcasts and Radio) are really, really slick. As a clever touch, the List view, pictured below, shows album covers on the left (which iTunes can now grab automatically from the store for all your non-iTS purchases), with a list of each song, artist and album name (somewhat redundant) for each individual album. TV Shows works the same way in that it organizes episodes by season. Very, very well done.
The new Cover Browser, the third option of the new view buttons just to the left of the search box, is really a sight to behold.
This features definitely steps on CoverFlow's toes in a big way, and I'm sorry to say - it's done a bit better. A scroll bar at the bottom of the cover browser is easier to click and drag with, and the animation is incredibly smooth and, dare I say it, sexy.
[Update: we have since learned that CoverFlow was actually bought by Apple. So instead of having their toes violated, it sounds like they came out on top with a good chunk of change. Good show.]
Unfortunately, I was surprised to find that these new view buttons don't work for podcasts. They're still listed and organized in the iTunes 6 fashion.
All the rest
There are plenty of other big changes in iTunes, ranging from a UI bump to the preferences, the ability to toggle displaying any of the media sections in the Sources list (which, oddly, no longer has any kind of name/heading), parental controls that allow disabling various sections and the purchase of various content based on PG/TV rating, a new dedicated Store menu for managing your account and purchases, and an appetizing new "Transfer Purchases from iPod" option under the File menu, finally allowing users to sync (at least some of) their music between computers with nothing more than an iPod and a cable.
There has to be plenty more in this major update, but this is the rundown of the big stuff for now. We'll be sure to post even more goodies as we uncover them.