But why ?
Spotify is my favourite place to listen to my music. Most the time I'm only streaming it from the web. When I'm on my phone it's pretty much all sync'd to my Android app. I'm FlobyIV on Spotify and FlobyIV as well on Last.fm
Because I love Spotify and Node.js so much, I couldn't help but give a try at using the first one with the second one. Spotify released libspotify some time ago, which is a low-level library (written in C) to use their service. It's not badly documented but it's probably the first time I had to bind to something without the ability to read the actual code, because libspotify is still proprietary software.
Try it out
I suggest you start by reading the Quick Start. Note that you will need to install libspotify globally on your system so that node-libspotify can link to it during compilation.
I wouldn't call node-libspotify a "finished" project. There are still some parts of the API that are not accessible from the Node side. But I'm still actively working on it, so it should be there soon enough.