there are major costs to support legacy and incompatible plattforms, costs mostly paid in additional workload and testing, loss of "agility" and speed. it's very impressive how far node.js has come in a very short time. yeah maybe the raise in market-share (and additional developers for the ecosystem) will be more valuable than the costs, maybe not.

i, as an egoistical dev-on-mac, would rather see a stable 1.0 for mac/unix soon, than a 0.8 for max/unix/win within the same timeframe.

as a thought experiment: would native max os x apps be as sophisticated as they are now, if all devs had decided to port them to windows (xp / vista / 7 / ...), too.