iPhoto+Trash

The trick is to select an image in your iPhoto Library and delete it by pressing the Delete key on your Mac’s keyboard. When you do this, the picture is transferred to iPhoto’s Trash, not the Mac’s Trash. To really, really get rid of the image, Control-click (Right-click) on the Trash entry that appears at the bottom of iPhoto’s Source list and choose Empty Trash. This gets rid of the image for good and all, bypassing the Mac’s regular ol’ Trash.

Notice that I said to select the image in your iPhoto Library. If you select an image in an album or slideshow and press Delete, the image is removed from the album or slideshow but not from your iPhoto Library. But there’s a trick here as well. If you select an image in an album or slideshow and press Command-Option-Delete, the image will disappear from all albums and slideshows as well as the iPhoto Library and appear in iPhoto’s Trash. Again, just access that Trash’s Empty Trash contextual menu to delete it from your computer completely.