Apple:

Version 10.0.1 introduces new features that make Final Cut Pro X even more flexible, powerful, and compatible. Download the update free from the Mac App Store.

For a x.0.1 update, this actually adds a lot of good stuff. The “Media Stems Export” and role assignment actually solves a pretty big problem from previous versions of FCP. The old way of doing this is way more confusing, which is why most people just screw it up.