You can now preview renderings of Markdown files that you edit in GitHub Gist.
It has long been possible to preview the Markdown rendering of file edits or comments on GitHub. But these Markdown previews weren't available for gist files. Now, when creating or editing a gist file with the Markdown (.md) file extension, a Preview or Preview changes tab will display a Markdown rendering of the file contents. This lets you easily switch between the source view and Markdown view of the file.
For more information about gists, visit Editing and sharing content with gists. Get started by creating a secret gist, or a public gist for sharing, at gist.github.com.