It goes without saying that the iPhone 4 has vastly improved camera features over the previous itterations of the iPhone. With a more powerful rear camera, a front facing camera (although it's fairly weak), and most of all, a flash, the iPhone 4 is definitely the most "camera oriented" of all the iPhones. And of course, the ability to record in HD video is a very sweet bonus!

In terms of photography with the iPhone, there's definitely more possibilities now than ever before. Low light situations no longer represent an insurmountable challenge, although the creativity previously used in dealing with such situations might suffer slightly. Trying to hold the camera to take a picture of oneself is virtually elimiated thanks to the front facing camera, although you'll still have to do this if you want a higher quality image of yourself.

But there's one feature of the iPhone 4's design that I think does make a significant difference in terms of photography, and that's the shape of the iPhone 4 itself.

The original iPhone was rounded and VERY slippery. You needed to hold onto the original iPhone with an iron grip so that it wouldn't slip from your hands. The 3G and 3GS were also rounded, but the plastic gave the phone a little bit more of a grip. The iPhone 4, however, is squared. You can hold it more delicately, without having to worry about it slipping or falling out of your grasp. For me, this is a significant design improvement which will definitely help me in my photography. Now, I can get the iPhone into more delicate and precarious angles without having to worry about my grip on it. This design change also has another added bonus:

You can now stand the iPhone up on its side. No longer do you have to try propping the phone up many different ways in order to take a picture without holding it. This is definitely a nice bonus, as I can easily place the iPhone on a table without worry if I want to take a timed photo of something.

So overall, I do think that the iPhone 4 has made significant improvements that are definitely going to help my iPhoneography, but the redesign of the shape, for me at least, is one of the most important, second only to the addition of the flash.