BlackBerryOS.comに更新内容がでていました。
（Twitter Updated To v4.1 For Legacy BlackBerry Smartphones ）Changelog for version 4.1:
1. More tools to discover friends, content and stay connected to your social networks.
2. Easier to sign up – signing up is easier than ever with pre-populated the name and email fields from your BlackBerry ID (BBID) credentials. All you have to do is enter a new password – it’s that simple.
3. Enhanced Profile – Enjoy an enriched Profile experience that has been redesigned with a swipeable banner of your bio.
4. Better notification support – The option to activate notifications for Retweets, Favorited tweets and new followers, means you’re fully in control of your Twittersphere.
パッと確認できたのはプロフィール画面で、ガラリと様変わりし9900では横スライドします。
その他BBIDとサインアップが紐付けされたり、通知がうまく動くようになっているようです（未確認）
