>[...] There are good reasons to think that the
>illusion of shared memory cannot be maintained in the presence of
>hundreds of computing elements, even using cc-NUMA techniques
>(i.e. hardware emulation of shared memory on top of high-speed
>point-to-point links).

I'm not arguing any of your points but just note that larger NUMA
machines than that are available and sometimes practical - SGI Altix
go up to 1024 cores with a single system image.

(To answer Richard Jones's question, I know Bea have tested their JVM
on such a machine but I have no idea whether it turned out to be
useful. I doubt there are many Java applications actually needing such
a wide JVM.)