This site is using the standard WordPress Theme Unit Test Data for content. The Theme Unit Test is a series of posts and pages that match up with a checklist on the WordPress codex. You can use the data and checklist together to test your theme.

WordPress Theme Development Resources

1. See Theme Development for code standards, examples of best practices, and resources for Theme development.
2. See Theme Unit Test for a robust test suite for your Theme and get the latest version of the test data you see here.
3. See Theme Review for a guide to submitting your Theme to the Themes Directory.