Some of the functionalities right now are: (1) Ability to save and tag tweets with urls (kind of Delicious) (2) Url content inline with the corresponding tweet

Some of the functionalities right now are: (1) Ability to save and tag tweets with urls (kind of Delicious) (2) Url content inline with the corresponding tweet (3) Search over all the tweets you could have seen. In other words, you can search over all the tweets of the people you follow.