"So we created webworker-threads, a cross-platform implementation of the Web Worker API for Node.js."
The AOSA article is a great read. Further, the result of that EtherCalc work is one of the coolest projects around- an implementation of Web Workers for Node.js using native threading:
"This module provides an asynchronous, evented and/or continuation passing style API for moving blocking/longish CPU-bound tasks out of Node's event loop to JavaScript threads that run in parallel in the background and that use all the available CPU cores automatically; all from within a single Node process."