Gist.GitHub is an excellent way of sharing code snippets. Google Sites is a great tool to build web sites, including documentation web sites. However, Gists cannot be directly included in Google Sites pages, as script tags are not allowed. The solution? Well, we just have to wrap the code to embed a gist in a web page in a Google Gadget. So, to embed a gist in your Google Site page, you just have to:
The gadget is hosted on Google Code.
As an example, here is the gist containing an older version of the gadget source code:
And here a longer public gist: