Interesting idea. But, if it would be very similar to Pinterest, it might be hard to market.
You need to have at least something that differentiates you or something that makes you unique so you could get to convince those people to switch to your site even though it would be quite similar to the boards they have been creating for those 'specific' hobbies.
thanks for your response. I know im not creating anything new but I wanted to use the script to have people upload funny pictures - relating to the stuff they see on the street. There are lots of funny posts, signs and etc that aren't standard in my country and I keep seeing people post such pics on Facebook with the term: "Only In etc..." etc... I figured if I have a page full of these pics, it would be easier for users to view all of them gathered on one page.