What happened to WinFS?

"I don't think anyone really knows.

The most up to date information I can find is an interview with Quentin Clark in which he says that ""most of WinFS either already has shipped, or will ship"" just in other forms, such as part of SQL server or the ADO.net entity framework.

I personally suspect it was one of those projects that was poorly defined from the start. It was all things to all people and consequently could never fully realise all it's goals. It seems that all the research that went into the various different aspects of WinFS eventually grew into separate projects and became parts of other things.

You can see from this development timeline that it's been an ongoing project since 1990. that makes it one of the few software projects that actually been in development longer than Duke Nukem Forever

[Edit: For completeness, here is some other info I found - WinFS Blog - Last updated June 2006. The last entry basically says WinFS was not dead but is no longer a separate product, it was planned to incorporate the tech into other products like SQL server and ado.net]

New information (May 2010):

I found this article which talks about the features of WinFS that have survived and live on in some form in Windows7."

"Hal Berenson, the General Manager of what would become WinFS wrote an excellent four-part blog series after Bill Gates disclosed in 2013 that his biggest regret from his time at Microsoft was the failure to deliver WinFS:

WinFS, Integrated/Unified Storage, and Microsoft – Part 1 (archive)
WinFS, Integrated/Unified Storage, and Microsoft – Part 2 (archive)
WinFS, Integrated/Unified Storage, and Microsoft – Part 3 (archive)
WinFS, Integrated/Unified Storage, and Microsoft – Part 4 (archive)

From thisisbillgates:

Q. What one Microsoft program or product that was never fully developed or released do you wish had made it to market?

A. We had a rich database as the client/cloud store that was part of a Windows release that was before its time. This is an idea that will remerge since your cloud store will be rich with schema rather than just a bunch of files and the client will be a partial replica of it with rich schema understanding.

The short version is that it while it difficult to pull off, the challenge was to get the Exchange team to use it. They were going to be the test case. Except Object File System (OFS, aka Integrated Storage, aka Cairo, aka WinFS) wasn't ready yet. Microsoft had just bought SQL Server from Sybase, and were also creating an entirely new database engine internally from scratch: Jet Blue. Does the Exchange team wait for Cairo? Do they move to SQL Server? Do they switch to Jet Blue?

In a meeting with Bill to decide the direction for Integrated Storage he had to choose between two options. One was the technology base that he thought was the right one for the long-term vision of Integrated Storage, but it was a store with no one committed to use it. The other was a solid plan and commitment to deliver something that unified the unstructured and semi-structured worlds within Microsoft. Bill chose to let the Exchange-based plan proceed, but also encouraged us to continue to work on SQL Server as the basis for a future Integrated Storage solution.

Exchange team went ahead and used JetBlue. The free database engine that ships with Windows, and has a publicly supported API. JetBlue, aka Extensible Storage Engine, is the database that powers:

Exchange
Outlook
Windows Search
Active Directory
Windows Updates

Bonus Reading

And in a vein similar to WinFS and data storage, Hal also had an excellent blog on the history of OLEDB, the visions, the promises, and how OLEDB really does solve problems that exist:

OLE DB and SQL Server: History, End-Game, and some Microsoft “dirt” (archive)

Along with SQL Server team's announcement that they're ending support for the OLEDB native client."