One of the new features of the 2.0 firmware is the ability to save photos from your email and from web pages in Safari. All you have to do is hold your finger on a picture for a few seconds. A little toolbar will pop up from the bottom and give you the option to save it to your camera roll. If the image is also a link it will give you the option to visit the link. The really nice thing about this is it’s saving the original file size. So once you plug your iPhone or iPod Touch to your computer you can pull the full resolution picture off.
TIP: I use this feature to steal pictures from my friend’s Facebook and Flickr accounts and use them as the photo in their contact info. :)