Origins of LINQ and the WinFS Black Hole
A fascinating blog posting from Matt Warrer of Microsoft on the origins of LINQ and how the technology escaped the black hole of WinFS:
Why didn’t I start with WinFS? After all, it was all the rage inside the SQL Server org at the time. Unfortunately, it was the same story as with ObjectSpaces. They were shipping before us. We weren’t on their radar. Their hubris was bigger than ours. Not to mention my belief that WinFS was the biggest fiasco I’d ever bore witness to, but that’s another story.
Yet, part of that story was the impetus to turn LINQ to SQL into an actual product.
Way back when I attended a multi-day WinFS event put on by Microsoft. When I got back to Adobe I wrote a rather scathing report on the technology, and predicted it wouldn’t ship in Longhorn. It was a somewhat controversial report at the time, and I was greatly relieved when my prediction came true. Its nice to see that there were folks within Microsoft who felt the same…
Tip of the hat to Erwyn van der Meer for the original link.
Shebanator 
It would be improper to say that LINQ was rooted in ObjectSpaces and WinFS, as it wasn’t. It is mainly the brainchild of Anders Hejlsberg.
It is correct that LINQ to SQL does have its roots in ObjectSpaces and WinFS, but only when fully specifying LINQ to SQL.
@Nicholas: point taken. I wasn’t trying to take any credit away from Anders or anyone else, just using shorthand. ‘LINQ to SQL’ doesn’t exactly roll off the tongue (or the keyboard).