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.
He was thinking of ads and also having specialized experts rate and give suggestions/feedback for a small fee.
My friend is thinking of this as a part business however, he is still in grad school and so can afford the loss of initial investment.
I personally did not like the idea, cause he would be competing with sites like Facebook and other social network websites + there are already lots of popular rating websites. But since you never know, I offered to help him for free.
I found a software and am busy installing it and customizing it as much as possible. Hopefully it will be done by next week.