Most interesting about Twitter's move is that these lists are going to be "public by default" even though you have the option to make them private. In fact, these lists are going to be linked from your profile, just like your messages and your favorites are today - letting other Twitter users subscribe to your lists, a big move forward for recommendation-based discovery, along the lines of "Follow Friday", but official.
Twitter's List Feature Displayed Via the Twitter Blog
As Twitter wrote in its official blog post today, they started to work on the feature thanks to "frequent requests" from people "who were looking for a better way to organize information on Twitter". And they promise that these lists will not be siloed on the Web site, but extended to other programs via a new API, enabling developers to add Lists support in their apps.
Interestingly, the Lists announcement comes on the same day that Lunch.com introduced their own ability to enable Twitter Lists. I hope to show you a few I was working on once I don't overwhelm the system. (I tried earlier today, unsuccessfully)
After some time where it has looked like Twitter was standing still, just trying to keep afloat, the features are making their way out the door, and they are welcomed for the many users who don't know where to go next once they have an account.