Slashdot post: WinFS Gets the Axe. commander salamander writes “Over at the WinFS Team Blog, Quentin Clark states that Microsoft no longer plans to ship WinFS as a standalone software component. Instead, portions of the underlying technology will be included with the next release of SQL Server (codename Katmai) and ADO.NET. Does this spell the end for the true relational storage paradigm that Microsoft has been promising since Windows 95?”
Yet another disappointment. The best lesson to walk away with is that you can never count on commercial software that hasn't shipped yet. There are a vast array of shipping file systems you can consider. If you have a need for a relational database interface to a file system, you could look at Gnome Virtual File System, the Be File System (written by two guys in 1996 over 10 months), Apple's Hierarchical File System Plus (1998) — interestingly, the file system of the iPod. For a deep backgrounder, Wikipedia has an interesting and heavily annotated article on File Systems.
It also points to another advantage of Open Source and the principle of “ship early, ship often.” If an Open Source project wasn't going the way you wanted, you can fork the code and create a new project following your directions (with proper attention to the original licenses involved, of course). You might search SourceForge.net for “database file system” and see if there's anything of interest. Seems like plenty of neat stuff.
A corollary of the first lesson is to never depend on roadmaps. Dates slip, market demand shifts, plans change. As the Register points out in “MS poised to switch Windows file systems with Blackcomb,” the best laid plans of mice and men oft go awry.