The Google Webmaster Central blog post about the service tells us
Until now, marking up your site’s HTML code has been the only way to indicate structured data to Google. However, we recognize that markup may be hard for some websites to deploy.
Today, we’re offering webmasters a simpler alternative: Data Highlighter. At initial launch, it’s available in English only and for structured data about events, such as concerts, sporting events, exhibitions, shows, and festivals. We’ll make Data Highlighter available for more languages and data types in the months ahead.
Data Highlighter is a point-and-click tool that can be used by anyone authorized for your site in Google Webmaster Tools. No changes to HTML code are required.
Can you hear many less than technical types saying “Thanks, Google!”?