The Twitter app for Android just got updated to v5 and it marks a significant changed when compared to the older version. One of which is the removal of the notification tab, before now notifications can be accessed by just swiping to the right but now it can only be accessed by taping on the bell icon at the top. A swipe to the right now takes you to the Discover tab (it seems Twitter is trying to force everyone to use this feature).
Another big change is the ability to share photos via Direct Messages, which is grreat news for some people.
Overall I can't say I like the new look, the whole simple and clean look brought in with the introduction of the Holo UI is beginning to make already great looking apps now look like what a 8 year old came up with.