I came across this blog entry talking about the new transactional NTFS in action ; very interesting and very cool (yes this is in Longhorn - you can check out some screen shots). What is more interesting is that internally people at MS have started using it, but the question that comes to mind is, is that outside of Longhorn (are there any bits running on Windows 2003 Server or XP, etc)?
If you’re in Microsoft, you can start using this today; if you’re outside of Microsoft, I encourage you to take advantage of the upcoming Longhorn beta programs and try it out.