I like some features of NodeJS, particularly JQuerification, websocket compatibility via socket.io, view and css engines that I cannot use with JSP (and of course, asynchron
I personally feel that NodeJs is nice to do some kicking around with. However I wouldn't put to use in a production environment as of now. Especially if the the production environment would be handling critical data.
I would probably wait until, it gets to version 1.0 at least.
But if you are planning on using it for non critical applications I would say go for it. IT is always good to start, and I guess as your application grows NodeJS will mature as well.
Then again this is my personal opinion. I have only used NodeJS in my side projects, I have never used NodeJs in any production environment.