Windows/Mac: Alongside the latest version of iOS, the newest version of iTunes is now available, complete with the Genius mixes and new podcast features.
While Australians don't have access yet to the new iTunes Radio feature, there are other changes that make this worthwhile. A new Genius Shuffle feature creates mixes of music in your library that (should) go together. Each time you click Genius Shuffle, you'll get a whole new set of songs to listen to.
For podcast fans, iTunes 11.1 will now sync your subscriptions across all your devices, and the new My Stations feature allows you to create a playlist of podcasts.
If you're planning on upgrading to iOS 7, you'll need the latest iTunes anyway, so it's worth grabbing (either directly from Apple's site or when the update is offered on your machine).