Twitter has just taken a step toward a richer social experience with its exciting new “lists” feature, which gives users the ability to organize individual accounts into groups. For example, a user can create and share a list of “celebrity” accounts that they follow. Twitter lists may be marked by their creators as public, or kept private for personal use.

In a move sure to be popular with developers, Twitter has added list manipulation features to their API (see our Twitter API profile). Last week, Twitter founder Biz Stone wrote about the significance of the Lists API on the Twitter Blog:

Lists also make it easier to curate tweets into meaningful real-time experiences on your own sites via the Lists API. Media companies are already taking advantage: for example, check out @huffingtonpost’s use of the Lists API in their World Series coverage… We’ve been taking our time rolling out the lists feature to make sure things go smoothly and developers have a chance to begin experimenting with our Lists API.

The Twitter API’s new list functions are still in private bet