True, Concurrency is not Parallelism [http://concur.rspace.googlecode.com/hg/talk/concur.html], but sometimes all you need is parallel execution of a single algorithm, and you need a set of primitives that succinctly and efficiently express that parallelism... not to mention integrated access to SIMD and GPUs, where only parallelism need apply. I'd say there needs to be both a high level "break your app's work into a heterogeneous set of processes" API, like CSP, and a low level "run an algorithm on this array really fast" API.