Twitter has been stepping up its presence in the mobile world. Until recently, it relied on third-party developers to create Tweeting apps and provide users with a variety of mobile Tweeting options.
However, as the userbase exploded, the non-techie crowds became confused by all the different apps without anything official from Twitter. So last month, it bought out the indepentent "Tweetie" app on the iPhone and promised to re-brand it as an official Twitter app.
So now, iPhone owners who search for "Twitter" in the App Store will find one app, simply titled Twitter, that lets them Tweet to their heart's content.
Twitter also recently launched official apps on Android and Blackberry, giving it presence now on all the major smartphone platforms.