A few days ago twitter announced a new image gallery and browser that makes it easier to view and browse images shared via 3rd party twitter image applications (at least up to 100 or as far back as January 1st, 2010). This feature is cool because it makes it easier for users to view their followers most current pictures.
This feature can be seen on a users profile page near the top right column under recent images.
It's always cautionary that you be mindful of what you share on the internet. Once it's in the so called cloud of the world it is very difficult to remove.
Twitters methods of integrating new features so far as been very seamless with little to no interruption to it's users. It's only a guess but the next feature they will add may be a video gallery feature similar to their new picture gallery.