Node isn't a 'new' language. Its not even a new engine. It's a JavaScript environment; just new members to access. The biggest difference between the JavaScript everyone knows('browser' JavaScript) and node is there isn't browser, window, document members. Instead you have 'server' members such as file and socket handlers. Most member calls are done through callback functions, which have the potential to speed up code(or at least keep your program from hanging), though to new JavaScript comers this can make code difficult to read and understand
I work with node quiet a bit just tinkering, and for simple projects it's amazing, but as you scale projects you will see a drastic decrease in speed; more exponential than linear. The more the interrupter has to handle the closer node comes to crawling by. This is by no means what everyone will experience, just what I have time and time again.
In my opinion, Nodejs is great for small, in house, projects but beyond that I'd suggest using something along the lines of Apache+PHP+MySQL.
I just discovered http://expressjs.com/ - This looks like a nice web server library for node.js
Was just looking at this article about using node.js with mongodb. This is a very nice combination of technologies in terms of speed and scalability.