This fea­ture for Niko­la was im­ple­ment­ed by @amok­leben, and now, if you ask twit­ter your site can have it too.

What are Twit­ter Card­s? Did you no­tice that for some sites, when you click on tweets that have links, you get a small pre­view of the con­tent? Well, that's a twit­ter card.

This still needs a lit­tle im­prove­ment to sup­port the rich­er "me­di­a" card­s, but it does work:

You don't have to do any­thing in your site, but set­ting the "de­scrip­tion" meta­da­ta to your posts helps make this more ac­cu­rate (and it al­so works for google+)