I'd like to build a (ruby) script that interacts with a github wiki.
Gollum seems to want to manage a local working directory.
Is it possible to interact directly with a github wiki?
No. due to the distributed nature of Git, you interact by pushing new commits from a local repo.
Even the latest Octopress blog (using rake command to create new post) is base don the local clone, and a deploy process to GitHub.