Node.js runs fine on Raspberry Pi (it's my test platform), and the code works great with the recent firmwares (otherwise you hit a bug that causes the Pi to freeze when doing serial interactions)
The rfxcom library is available from:
I also, as an experiment, wrote a simple xAP broadcast class for Node.js, which is capable of sending xAP formatted messages:
Have a look at the example in the node-xap README.md for how to connect the rfxcom and xap libraries together...it's fairly trivial...
This is just simple xAP broadcasting, but I'm working on a parser for xAP messages, which would allow more complex apps to be built.
In saying that, am not convinced of the current utility of xAP as a protocol, no security, UDP, custom payload format etc., and I've outlined some thoughts on how it could be improved here http://bigkevmcd.com/2012/10/xap-protocol/