I just thought it would be worth mentioning that thanks to a lot of hard work by people in the Node community, the module that our CLI relies on for serial communication with devices has now been made compatible with the latest version of Node. I have published a new version of the Particle CLI with its dependencies updated to use the compatible version of the serialport module!
If you end up having any trouble using the CLI with Node 4.x, please feel free to post here or create a new issue!
Please; go forth and utilize this newfound compatibility for ultimate win and great justice. If you are excited about this (and have a GitHub account) please take the time to post on this thread thanking everyone for their hard work!