The camera borrows a feature from windows phone by allowing you to swipe to the right after taking photos to quickly view photos you've taken. You can then pinch to show a big list of the recent photos snapped. From this list, you can swipe photos up or down to delete them. When you delete photos there's an undo option in case you deleted the wrong one.
The notification improvements look really useful to me. They now allow "rich notifications" which allows developers to add actions to notifications. This means, for example, a missed call notification could show two buttons along with the notification; call back and message. The notification at the top automatically shows the extra actions, and to show extra actions on any other notification you just swipe down with two fingers.
Here's a picture:
http://www.google.co.uk/search?q=je...oAQ&biw=768&bih=928#biv=i|0;d|KbJfJaKyDzvaHM:
As you can see, you can email guests invited to an event directly from the notification bar. Pretty useful.