Twitter launched a new feature called Twitter Custom Timelines that allows users to curate tweets within a stream. The new feature is available through Twitter's developer center (dev.twitter.com) or available to users through TweetDeck. Users can select specific tweets that they want to include in a custom timeline, which provides a wide range of creative outlets. For instance, a news website may curate tweets related to an emerging news event, which will help provide a bird's eye view of a story.
See below for a spotlight example offered by Twitter in their developers' area.
Custom timelines are now publicly available and have a dedicated page on Twitter.com. The Twitter developer area also has a publicly available custom timeline API beta, but web developers will need to apply to be able to access the API. This will allow web developers to programmatically design their own custom timelines.