While you can view and edit your camera roll directly from the iPhone's camera app, iOS 5 now contains a new shortcut that lets you instantly swipe through recent photos.
To use the shortcut, just open up the Camera app and swipe to the left. It'll instantly go to your most recently taken photo. You can keep swiping through your camera roll from there without opening up the full-fledged camera roll, and swipe right back to the camera interface when you're ready. It isn't a feature that was lacking in iOS, but it's a pretty nice shortcut if you want to check your most recent photos. Check out the video above to see it in action.
iOS 5: Shortcut to viewing photos from Camera app [Mac OS X Hints]