Here's a short link to a post on frontiernews.org which is a WordPress.com site.  

According to Matt, if I post the shortened link to Twitter, the text of the post will show up there. Let's see. 

Twitter thinks there's some "media" there, but it doesn't display it correctly (it does open up a space for it). 

So there's some evidence of a connection here, but not sure how much or what it's supposed to do. 

Update: After a more careful read, there's documentation here for their support for oEmbed. There's also information about a few other services. What about the other 18 billion websites? How do we find out about their oEmbed support? 

Here's the request for the frontiernews.org post mentioned at the top of this piece. 

The big question is why isn't everyone using the <link> method for discovery???