The API is currently down: https://status.github.com/

Fortunately, I implemented a cache layer on top of GitHub's API recently, so many examples are working on http://bl.ocks.org. But only those that are lucky enough not to get a connection timeout. Hopefully the API will be back up soon!

It seems like the Gist component of the API is either having a hard time or no longer works with JSONP.

I'm also having an issue with Plunker as legacy templates are pulled from Gist and are currently broken.