I think what
BrowserUK said is that (at least on hardware of the forseeable future) all methods of concurrency (except cooperative events, eg: POE) are necessarily based on something like
is or
works like CPU threads.
I would tend to agree that the "Threads/Processes and Locks" paradigm is a terrible high-level concurrency abstraction... much too easy to make mistakes, and it's hard to apply to the majority of algorithms and data-structures we're all familiar with.
I'm interesting in how we might tackle some of the more (currently) esoteric concurrency abstractions in Perl.
-David.