For years and years now I've wished that Photosynth.net content would preview on Twitter, embedded in tweets that linked to it in the same way that Vimeo or YouTube or Flickr or SoundCloud media does.
This allows Twitter users to check out that video/photo/panorama/audio without ever leaving Twitter.
I never looked into what was involved in getting this to happen. I just sort of assumed that Twitter did it for high profile media sources to keep their users on Twitter, rather than getting distracted on the target site and that lower profile media sites would have to beg and plead with Twitter to get their content respected in the same way.
Today I happened across old information that websites can do this for themselves by adding the Twitter Cards HTML code to their site. https://dev.twitter.com/docs/cardshttps://dev.twitter.com/docs/cards
So my question is, "What's the hold up?"