Here's an undocumented feature of the new Mobile Safari, when you run across an image on any web page accessed through Safari, touch and hold it. A menu will come up asking you if you want to save it, if the image has a link, you are additionally asked if you would like to jump to the link.
The image is stored in your Photos app. Handy for finding pictures of people in your address book and adding it to their contact file!
