I've asked more than one geek of admirable mental stature what seems like a simple question: How does one delete many or all of the photos stored on the iPhone? The usual method -- deleting images as you import them to iPhoto -- doesn't work. Each scratched their head, and in the end reported that one had to delete them from the iPhone camera app, and do it one at a time.
Nuh-uh, that can't be.
And, thankfully, it isn't. But... what it IS is far from intuitive.
1. Connect your iPhone to your Mac. Duh.
2. Open Image Capture, click “Download Some…”
3. A window displays the iPhone's camera roll. Select one/some/all of the photos you wish to delete, and then under the Edit menu, choose Delete.
That's it.
