I was looking for something like this for quite a while. From time to time, I want to write about code organization, but always struggle on how to present that. Being able to embed a Github repo in a post seems like a great way of doing that. Its not like I would embed the repo of an actual, big project.
I would recommend allowing one to set a max height. It's rather impractical to have a 200px tall box turn into an enormous box with 500 lines of CSS.