It's a command line client for Courier, written in Ruby!
With a version of Ruby (>= 1.9.3) installed, do:
$ gem install courier_client
$ courier config API_BASE_URL ACCESS_TOKEN
For example:
$ courier config https://courier.myhost.com/api CKXsr6npvUQTWWvX96gabQ
This will create the file ~/.courier/config.yml to hold these values.
To send a message to all of your devices:
$ courier send 'Something important just happened'
To send a device to just one of your devices, use the --device (-d) switch.
$ courier send 'All done!' --device DEVICE_NAME