From what I understand, the significant improvements in speed come from Crankshafts tradeoff of compilation optimisation for startup speed. If your app is a for loop with 2 iterations that code path won't be heavily optimised as the interpreter would potentially be more spending more time compilation code than in execution of unoptimised code. It will therefore startup faster. However, hotspots (loops with 1,000 iterations, per se) will be heavily optimised.
This is great for websites as speed and responsiveness is perceived as startup time. You'll certainly notice a difference when using the Node as a scripting tool. However, most Node applications are long running servers executing the same code paths over and over. Its unlikely that Crankshaft is performing any extra optimisations, it is just changing when it performs these optimisations. However, if Crankshaft _is_ doing significantly more advanced optimisations (I don't know) then, yes, Node will benefit. Please correct me if I am wrong, I would love to be.