What is Transactional NTFS?  Transactional NTFS is an enhancement to NTFS that allows all file operations on an NTFS file system volume to be performed within the scope of a transaction.  This is made possible by a new transaction infrastructure in the kernel that allows operating system services to participate in transactions via the new Kernel Transaction Manager.

What scenarios does this enable?  Transactional NTFS is also fully capable of communicating with the MS Distributed Transaction Coordinator, meaning that TxF operations can participate in transactions that leverage any other Resource Manager that DTC is capable of working with.  What does this mean to you?  It means that you can now have an application that not only encompasses database calls, but also operations to the file system as well (think of Document Management solutions).  With transaction enhancements being made to the new SMB 2.0 protocol, you can also now contain distributed file operations within a transaction as well.

To learn more:

Documentation
Windows SDK

Videos/Webcasts
Vista Transactional File System [Video]
The Revolutionary Vista TxF Infrastructure [Webcast]

Blogs
Jim Johnson
Jason Olson