In addition to the big google projects using it (Chromium, V8, WebRTC/jingle, etc), there's also Joyent's Node.js (and forks, + numerous node packages containing native code), as well as numerous private projects that I've been involved with. Unfortunately, it hasn't taken off too much in the open source community apart from the above mentioned big name projects. Better documentation and more visibility could probably make that happen, though.