What did I tell ya? Confirmation via Wilco that the upcoming EP/extra disc won't cost you a cent if you already bought a ghost is born:

For those of you who already own a copy of the CD it will also be available as a FREE download via the enhanced content on "ghost", meaning you'll be able to access the download only with the CD in your computer drive. If you purchased ghost on iTunes, it will also be available there as a stand-alone item.