Joel, selling the prints I don't see a need to hurry out and make an LLC. Keep in mind at any time you can change from sole proprietor to LLC. If you start taking on clients do it.

I think what would be more important is good liability insurance. I know general liability would be a necessary in case you accidentally hurt some one, I am not sure what other types of insurance a photographer might carry. Here is an instance, if you have been watching USA olympic basketball a player on an opposing team ran in to a photog and hit his head on his big white lens a game or two ago. Imagine if you were at the local high school game and the top prospect in the country ran off the court and was knocked out by your lens. Big lawsuit, an LLC might help you but probably will not in this situation.