Hi guys,
I am trying to figure out if there is any way to run a custom script once the image has been uploaded. I'd like to run some APIs (Facebook, pinterest) in order to publish the image as soon as it is uploaded, any idea?

You would have to write a plugin and hook into filters:
http://www.zenphoto.org/news/zenphoto-plugin-architecture

Thanks, I'll have a look on it!