Looks like Microsoft has made available the very first update to Office 2013 Customer Preview. Office 2013 was made available to the public as a Customer Preview on the 16th of July and this update should bring some stability and bug fixes.
Stay tuned as we try to attain an official change log. With any update, it is safe to assume that this update brings stability enhancements as well as bug fixes to the Customer Preview build of Office 2013. On top of that, this update brings Click-to-Run virtualization fixes to Office 2013. Looks like this update can be pulled when you launch an Office app, hit File, then select Account. Under Office Updates, you can see the update and choose to disable updates or prompt you for any updates.
Thanks anthonymel for the tip!Further reading: Microsoft, Office 2013