Automatically... not exactly. All your Photo Booth pics are put in your ~/Pictures/Photo Booth folder. You could make an Automator action to have the computer put them in iPhoto for you, but it wouldn't do it instantly. You'd have to run the script manually each time you wanted them put in iPhoto.
You could save the script and then have Automator or AppleScript run it at a certain time each day, which would update iPhoto. Or maybe you could have it set to run each time you login.