Today (26th of May) Google updated their Introduction to Structured Data page to include:
In addition to these specific features, Google can make general use of the sameAs property, alongside any other Schema.org structured data present, to understand better the meaning of Web content in terms of identifiable entities and relationships.
To me, this is a good step towards true linked data. In it’s simplest form, you could mark up any line of text as a “Thing” and include a sameAs property linking to the things website:
<span vocab="http://schema.org/" typeof="Thing"> Apple <link property="sameAs" href="https://apple.com"> </span>
<span vocab="http://schema.org/" typeof="Thing"> Apple <link property="sameAs" href="https://en.wikipedia.org/wiki/Apple"> </span>
Google can then gain more understanding of what you’re talking about