The idea sounds fun and there will be plenty of free scripts out there that should be able to make it work. The main problem I see is making it worth while. Images use a lot of bandwidth, and this costs money. Does your friend have any ideas on generating revenue?
There are also a lot of sites out there offering a similar service. You need to be creative and offer something unique.
If you are simply doing this as a fun project then go ahead! But if you are looking at this as a business then you will need to plan very carefully.