Nothing new here, I already wrote about this using node.js, Automator and osx http://explorejs.com/posts/using-two-nodejs-applications-to-... and the code is open sourced on GitHub

I really like the idea. Maybe you could also add a prefix to the file and have it automatically upload into that folder. Lets say st_background.png and it will automatically upload to your static files folder and app_img_filename.png will upload to app/img/