Is there a way of making iPhoto's Photo Stream one-way sharing? As I don't want all the pictures I download from my regular camera on iPhoto to be shared with my iPhone or iPad.
Under iPhoto / Preferences / Photo Stream you can disable Automatic Upload. When turned off, you'll have to manually select which photos will be shared on the Photo Stream.
There are several ways of manually adding photos to the photo stream. After selecting the photos you want to share just: