What is "tweetie"

Tweetie is a client for the social networking website Twitter. There is a mobile version that runs on iPhone, iPod touch, and iPad, and a desktop version runs on Mac OS X Leopard, Snow Leopard and Lion (respectively 10.5, 10.6 and 10.7).

Both the iOS and Mac versions of Tweetie were acquired by Twitter on April 9, 2010 and were re-released as the official Twitter clients for iOS and Mac.