Saving screen shots automatically should probably be default feature on any platform. This is a tip how to make it possible on Linux/Gnome.
Software to use
The default package which provides application to handle screen shot taking on Gnome is gnome-screenshot (Fedora 17, gnome-screenshot Version 3.4.1):
yum install gnome-screenshot
The application can run from CLI to take screen shots:
Of course, it also has GUI to sets various options:
However, the GUI doesn't provide one more option - a directory to automatically save all screen shots. In order to set this option, install dconf-editor package:
yum install dconf-editor
Run dconf-editor, navigate to org/gnome/gnome-screenshot, and specify any directory where all screen shots should be saved automatically, for example, file:///home/user/Pictures/screenshots.