When confirming a large number of Faces in iPhoto '09, you probably already know you can drag across multiple photos to accept them all at once. Sometimes, though, you might want to reject a group of Faces instead.
To do this quickly, just drag across the photos while holding down the Option key. You can also use this hint to reject individual photos without having to double click them -- just hold down the Option key and click on a particular photo to reject it.
Mac OS X Hints
http://hints.macworld.com/article.php?story=2009013020523438