The second release update to Node.js is out today.
"If someone new connects, then it executes the callback." According the Node Web site, "Each connection is only a small heap allocation."
Version 0.2.0 fixes several critical bugs including an OpenSLL 100 percent CPU usage on error bug. Node is now built with V8 2.3.8.
To understand Node, visit Felix Geisendorfer's blog post "Understanding node.js."