Here's a Camera shortcut which I think is new to iOS 5.
You can swipe to the right on the Camera app to see the last photo you took -- and continue swiping to see the rest. Swipe back to the left and you're back in the Camera.
[crarko adds: Nice touch.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20111026124029356