So, after a terribly frustrating day trying to get a huge .pdf into something that might be acceptably viewable on my iPod Touch, I tried deleting various test photos from iPhoto.
Delete. No freed up disk space. Delete another event. No freed up disk space. Small tick in the back o’ my noggin.
iPhoto has a separate Trash. Which needs to be emptied by hand. Go check your iPhoto right now, I bet most of you have been happily deleting photos without even realizing that they’re not actually gone.
I checked preferences and didn’t see any way for it to empty on quitting so it looks like we’re stuck remembering.