Drag and drop from iPhoto may remove the pictures from iPhoto Library, how to recover it? I modified the "Recursive Image File Processing Droplet" example provided from Apple in AppleScript Editor to rename any dropped file and move it to a custom folder. It worked seemingly flawlessly when I dropped images directly from iPhoto. Unfortunately I noticed now that the files where moved out of the iPhoto Library. So now the iPhoto Library is corrupted and iPhoto show the files I processe.

First of all when I dropped the files on my droplet it showed reassuringly the green "plus" sign, so I thought it was actually providing the droplet a copy of the file. Isn't this a sign of bad user interface?

Now, I'd like to know how to deal with the corrupted iPhoto Library and the missing pictures. So my real question is how to recover a corrupted iPhoto Library in the most painless way, when all happened is that some files where renamed and moved away. I wrote all the story as a warning for people who may do the same thing.

My system is OS X 10.7.4 and I am using iPhoto '09 8.1.2.
Most painless way: Restore from back up.

Assuming the photos haven't actually been deleted, but instead some form of database corruption:

Option 1
Back Up and try rebuild the library: hold down the command and option (or alt) keys while launching iPhoto. Use the resulting dialogue to rebuild. Choose to Repair Database. If that doesn't help, then try again, this time using Rebuild Database.
 
If that fails:
 
Option 2
Download iPhoto Library Manager and use its rebuild function. (In Library Manager it's the FIle -> Rebuild command) 

This will create an entirely new library. It will then copy (or try to) your photos and all the associated metadata and versions to this new Library, and arrange it as close as it can to what you had in the damaged Library. It does this based on information it finds in the iPhoto sharing mechanism - but that means that things not shared won't be there, so no slideshows, books or calendars, for instance - but it should get all your events, albums and keywords, faces and places back.

Because this process creates an entirely new library and leaves your old one untouched, it is non-destructive, and if you're not happy with the results you can simply return to your old one.   
Regards
 
TD