Apple have at last, after much delay, released iTunes 11. It has been completely redesigned with a new interface. However to most it'll look the same because the colours are the same, it's just the icons and layout have changed around a little. The main interface has changed, now there is no sidebar like before and you're given a gallery of all your albums. Of course you can still go back to the list view by clicking on "Songs". You can also quickly look at related songs and albums by clicking on one of your albums in your library.
There are a host of other UI changes which you will experience when using the new iTunes. So it's worth downloading and having a look around.