I like the new Hootsuite application for the iPhone, but it takes a while to move from one feed to another. I love the tab+columns view on Hootsuite's Web version. I wish that could be replicated or that you could have something similar for the iPhone app. TweetDeck has nicely implement column views and it much easier for viewing and reading tweets. If you had a TweetDeck-like column view along with column organized by tabs, you would have an incredible Twitter app.