When you Control-click (or right-click) an image in Safari 1.3 or later, you may notice that the "Save Image As" command in the shortcut menu has changed from previous versions of Safari.
Before Safari 1.3, when you chose Save Image As from the shortcut menu, you got a standard save dialog. In Safari 1.3 or later, the menu now includes a "Save Image" option that names your default download location in the menu. For example, the menu would say "Save Image to the Desktop" if you haven't specified a different default download location.
You can still access the "Save Image As" command if you want—just press the Option key after opening the menu.