The official Twitter for Android app has been updated with two small but notable improvements today -- a new reply screen and the ability to share tweets to direct messages. In version 4.1.3, the new reply screen resembles closely the general "compose tweet" screen with the ability to add location and pictures right from the window. Twitter says this makes it "easier to join conversations", but really it just means you get the same features when replying to a tweet as you do when composing one stand-alone.
Additionally, when you hit the share button on any given tweet in the app, you now have the option to share it as a direct message (DM) to another user rather than retweet and mention that user publicly. Once selecting the sharing option, you just type in a user name, add any additional words (up to 140 characters, of course) and send it off.
The latest version of Twitter for Android can be downloaded from the Play Store link above.