Public driven CMS?

I want to start a new BIG PROJECT!!! that will take ages and I came up with an idea based on the web 2.0 fad, well I want to make an easy to set-up CMS that is user-driven, I wont need help making it (just time).

AND NOW FOR YOU! I want to know, is there anything similar already? I was hoping this HASNT been done before!

NAME: Yes I already have a name WHICH is DigitalCarnivalCMS (it has meaning if you look at it carefully)