ShoutOut is a nifty (free) application for your iPhone/iPod that allows you to talk your way through tweeting, Facebook updates and texting.
What was unique about the updating was the rolling list of words as it guessed what you were saying, and allowed you to delete and select words with your finger quickly. You can also shake the device to clear the new message and start over. Simple, intuitive and free. It shows when it is listening and you can see the words it is selecting to send as you talk.
Note, if you click the link it will attempt to launch iTunes. Just hit cancel and you can view the webpage if desired. There are also more screenshots available to see the user interface.