I think that the line between "operating system" and application framework is a bit fuzzy, to say the least. I would argue that the Java VM is exactly an operating system to the code that uses it: a system of operation defined by the primitives presented by the VM. In fact, a VM and a set of APIs is all that a "real" operating systems is!

I can see why the title might irk you, but if you read the post, we're not claiming that it's another operating system to list besides Windows, Unix, OS X, and VMS, but rather that we've built an abstraction that has the same power, robustness, etc. for analytic tasks that an operating system does for simple processes.

The history of computing is one of building abstraction upon abstraction -- it's not like we built the OS and we're done.