One of my favourite Apps on the iPhone at the moment is TweetSpeaker
This App will be very convenient since I'll be doing a lot of walking during the snowy winter season, I'll put my headset on press play and walk to the train station while listening to all the tweets.
Its very easy! You log in (just the first time) then tap the play button and have your tweets read out to you automatically.
The App has a very easy layout, at the very bottom there is the Voice button (allows you to choose a voice), the play button and the Airplay button. Above it is your timeline design as a Radio dial.