On the Drupalize.me site they've posted a guide to getting started with Drupal 8 based on the boilerplate code that already comes with the release.

Drupal 8 represents a lot of changes and a steep learning curve for many Drupal developers and themers. While many of these changes are exciting, there are many things to learn just to get started. One way to learn about the code involved with Drupal 8 modules and themes is to take a look at core's modules and themes for examples to follow. Another is to use a code-scaffolding tool like Drupal Console to generate boilerplate code and comments that you can learn from and then customize.

He makes the assumption that you already have a development environment set up and working then helps you install the Drupal Console for use in the rest of the tutorial. You can then use this command line tool to create a new Drupal 8 installation and generate the boilerplate code for a new theme. Finally, they show the creation of the two other related components: a new module and a block plugin instance. These are generate generic code you can use as a reference point for either updating your current Drupal projects or create new ones.