If you want to create a github repo with a wiki, feel free. I have used github wikis in the past for hacking events, and I have found them disappointing. The bar for entry is high enough that most people don’t bother editing them unless I spend my whole time forcing them to.
So I have decided to try something different for the “record progress” part, which is to create a dedicated Discuss thread (not created yet) where people would just post a message.
I don’t have a specific plan for the “list of possible projects” angle (especially no plan where people could edit the page in real time to indicate what they are working on; I think most people won’t bother doing it anyway). If you want to create your own list as a wiki, feel free to. Otherwise I count on chat discussions and the already-existing documents that I would link from the announce page, in particular Awesome OCaml, to stand for themselves. (Feel free to suggest other sources of ideas to include in this page.)