The development team at Twitter has released a mockup of its forthcoming "retweet API"--basically, the first formal way that Twitter has baked retweets, the copying and attribution of other Twitter users' posts, into its own product. It displays the user avatars of members who have retweeted a given tweet below the original, "collapsing" them into a single space.
Some background detail on the forthcoming new API: Retweets have been a mainstay of Twitter for some time now, but the feature was created by users rather than officially. Several third-party Twitter clients have built in retweet buttons, and some apps, such as Tweetmeme, have created a way to tabulate them like a Digg count, but it's never been worked into Twitter's Web site or API.
What's interesting is that the new format, assuming that this is how the timeline ends up looking, can provide a quick, one-glance way to see just how influential a given Twitter user or individual tweet is, adding a new dimension to measuring Twitter influence beyond the follower count. If you see a lot of little retweet icons, for example, you might stop and take a closer look at a tweet (or the user behind that tweet) that you might otherwise have skimmed past.
What's also interesting is that it looks like retweet counts get cut off at 100, with higher ones displayed as simply "100+." I'm guessing that, say, CNN Breaking News generally gets a lot more than that.
When they were announced, the changes to Twitter retweets weren't met with a thoroughly warm reception. "Asking developers to collapse retweets in timelines is onerous, complicated, and confusing," the forum post by Twitter's Marcel Molina said in response to developer concerns that the collapsed-retweet format would do more harm than good. "We're not going to do it that way. We are going to add a resource that gives you all retweets for a given tweet. In timelines, you will get only the first retweet. You can then request all retweets for that tweet at any time to get up to 100 retweets that have been created for it."