Twitter announced late Wednesday that it is starting a limited test of a new feature that displays the number of new tweets in your timeline since you last refreshed. This works in much the same way as the new tweet notification on the search page for a term. When you click the notification, the new tweets slide out in the same fashion as the search page.
While this functionality was probably not too difficult to implement, since it was already built for the search feature, it is a welcome addition and something that just makes sense. In fact, it would make a lot of sense for Twitter to build out a notification system for @replies, re-tweets, and direct messages, like Facebook has for Wall posts and other actions. Getting updates without having to manually reload the page is one of the big advantages of Facebook's current functionality, so I would not be surprised to see Twitter to follow suit.
While this feature is still in limited testing, Twitter says it hopes to roll it out to everyone as soon as it can. I, along with many others, am not in the test group yet, so please share your thoughts on the feature in the comments if you are.