We're looking at tweets that have come into my timeline. As you can see, they're listed in reverse chronological order - no big whoop there. However, you can scroll back quite a distance, which IS different.
Here I've tapped on a tweet by TUAW editor Mike Rose and revealed the twitter conversation between him and the wonderful MacMommy. Note how the first pane has moved to the left, and the conversation is floating over the list of tweets.
Here I'm looking at my profile information. At the bottom of the screen is a list of Twitter users who are "similar to" me. If I click on Guy Serle, I see his list and other people who are like him... Pretty cool way to find new people to follow on Twitter.