Twitter is rolling two new features, Username and Activity Tab. They will replace the current Mentions Tab. As of last check, I still do not have these new tabs yet.
So, basically, these new tabs will provide more information as compared to the Mentions tab. That means that all Twitter apps will need to be updated.
Just click on the new tab with your @username, and you’ll be able to see which of your Tweets are Favorites, plus the latest Retweets (of your Tweets), Tweets directed to you, and your new Followers.
It provides a rich new source of discovery by highlighting the latest Favorites, Retweets, and Follows from the people you follow on Twitter – all in one place.