Chances are you have run Paranoid Android or Some other custom Rom that includes a forced tablet UI option. These mods change the DPI and force your phone to act like a tablet. This might be fine on a Galaxy Note, but what if your phone has a smaller screen. The tablet UI really is ideal on larger tablets as it is mostly functional with two hands. Sometimes it can feel cramped on a smaller screen. One of the best parts of the tablet mode is dual pane apps. Thanks to developer "DAGr8" you can have tablet apps without the full tablet UI! So far he has modified Gmail and Gtalk, but he is working on many other apps. He is also currently working on Untablet mode apps for large tablets. To install these you will have to remove the stock versions first.
More info via XDA