I noticed this yesterday when I dragged the app onto Script Editor. No Scripting Dictionary Found...
I think there's a good reason for this... you don't want someone scripting iPhoto to do a 1-click purchase of photo prints and hard bound books to their address... especially if you happen to have remote apple events turned on and an easy to guess password.
It's a bummer that it isn't scriptable though. Perhaps in a future version they could ask the user during installation if they want AppleScript support installed, along with an explanation of the consequences... mind you Apple probably wouldn't want to suggest to their users that AppleScript is a security threat.
That said, I really want to find the time to download the iPhoto scripts to see HOW it's doing the scripting!