Twitter's just unveiled a new offering that'll surely delight organizers and curators everywhere: It's called Custom Timelines, and it lets users compile a list of selected tweets in any order for others to look at — whether on Tweetdeck, embedded in a Web site or on Twitter.com. For things you want to keep a record of but don't necessarily update very often, this can be a good way to hand-craft (and share) an archive. For instance, if you're an app developer, you might build a custom timeline that functions as a changelog, helping people understand how your app has evolved over the past few versions.

Of course, Custom Timelines looks pretty similar to another curation tool — Storify. Storify offers a bit more functionality in that you can pull in more than just tweets; also available are Instagram photos, YouTube videos and other forms of media. Still, it's not hard to imagine Custom Timelines drawing away some Storify users simply because it's more tightly integrated within the Twitter ecosystem.

It's reminiscent of Twitter's earlier moves to clamp down on the third-party Twitter app market, which used to be a dynamic (if chaotic) place. In 2010, the company acquired the developer behind Tweetie, one of the most popular Twitter clients on the Mac platform at the time. That was followed a year later by a $40 million-plus deal to snap up Tweetdeck.

The pattern stretches back even further to Twitter's very early days, when the service didn't support one-click retweets, hashtags or a convention to address other users. People had to make those up as they went along. It took nearly two years for the so-called "manual" retweet (in the format "RT") to catch on.

Even though Twitter has a long, tough climb ahead if it wants to fulfill investors' expectations, the fact that it can — and does — draw inspiration from its own userbase gives it a significant boost. (A spokesperson for Twitter did not return requests for comment Tuesday afternoon.)

Update: A Twitter spokesperson declined to comment.