It seems to me it would be very useful to use Javascript for general server side scripting tasks as it has more or less the same features as Perl and Python. But AFAIK there are no generally available Javascript interpreters for the major machine architectures. I guess the other problem may be lack of libraries but surely these would come if the interpreters were there. Google's V8 maybe could be a starting point. Does anyone think we'll see this soon?
Node.js is exactly what you're asking for ... and more.

In addition to being a JavaScript runtime it also provides APIs for common operations, such as file system access (JavaScript on the browser doesn't really need that) and network IO.

It's marketed for building network application (and it's great at that!), but it's really a general purpose JavaScript runtime that you can use to build anything you want. Also, it is based on V8.
