Head over to https://git.matrix.ac and you will see a list of repositories stored on the matrix.
To host a public repository place it in
You can then add it as a remote, using:
git remote add origin matrix.ac:public_repos/<repo>
And you can clone via SSH:
git clone matrix.ac:public_repos/<repo>
And you can clone via HTTP:
git clone http://git.matrix.ac/<user>/<repo>
Currently there are no groups or finer permission. If this is wanted we can work something out.