Here is the feature a lot of you were waiting for: iTunes in the cloud. This new feature will allow you to sync your songs purchased in iTunes across all your devices. Let's say for example you download a song on your iPhone, you can then grab your iPad, see your purchased history, and decide to download all or individual songs to your iPad, at no additional cost.
Even better, you can turn a setting on so the song you purchased are automatically downloaded to your other devices. This is just a killer feature...