While one popular social network’s relationship with Twitter is souring (well, it’s already pretty sour), another is expanding their relationship in a way that will delight users of both services.

Pinterest has officially added support for Twitter Cards, meaning that Twitter users’ cross-posts from Instagram are now able to be expanded into media-rich “cards.” More succinctly put, your Pinterest photos are now visible on Twitter. The Daily Dot confirms that Pinterest added the Twitter Cards support last week, just as Instagram was pulling it’s support.

As you probably know, Instagram wound up going further in dismantling its relationship with Twitter. A few days after revoking Twitter Cards support (which made inline photos in expanded tweets appear cropped), Instagram cut off all ties with Twitter. All Instagram photos are now gone from Twitter – both the stream and in photo galleries. Users can still post Instagram links within their tweets, of course, but in order to see the photos users will have to click the link and navigate away from Twitter.

Pinterest, on the other hand, is integrating even more into Twitter by allowing shared photos to appear in users’ expanded tweets. Pins will not show up in Twitter’s “recent images” widget, however.

Here’s an example of what you’ll see in an expanded tweet when a user tweets out a pin:

As Twitter and Instagram continue to beef, Pinterest is making a move that shows it’s not worried about losing visitors to its site. Expanded, media-rich tweets are a great addition to Twitter and the more social media sites that allow for integration, the better it is for users.