It appears that Twitter is looking to give users more context about the photos others share in tweets – or at least make it easier to determine whether or not “clicking to expand” is worth their time.

A small number of users have noticed that Twitter is showing small thumbnail image previews on the right-hand side of tweets inside the stream.

Of course, users have been able to see photos (and videos) in-stream ever since Twitter debut Twitter Cards, but this is the first time the company has put images in tweets that do not require an extra click from users.

Here’s what it looks like:

Now, this is a pretty cool feature for users – but it’s probably an even bigger tool for marketers who are spending tons of money on promoted tweets. Just another way to catch an eye, right?

Of course, there are ways to do this already – for instance using a Chrome extension called Previeweet. Not only will that let you see thumbnail previews from pic.twitter.com, but also from services like Instagram, Photobucket, Facebook, Imgur, and more. If Twitter does roll out this feature to the masses, it’ll be interesting to see exactly which types of photo links it decides to show in its previews.

I can think of one that it probably wont show…