Changes to the Retweet System As of August 14, 2009 there is no true standard “Retweet” system. The only common aspect of a “ReTweet” was notifying whoever originally posted the tweet somewhere within the message.
Retweeting Example Edit
Original Tweet Bob: Please do not retweet this tweet Twitter Standard Robert: RT @Bob: Please do not retweet this tweet Tweetie Bobby: RT Please do not retweet this tweet (via @Bob)
Stone and Chief Executive Evan Williams use a non-standard format, according to the L.A. Times 
Robbie: Via @Bob “Please do not retweet this tweet”
While most Twitter applications use the Twitter standard, the key practice is some method of notifying the original poster that their message was being shared, via the notify @username.
Proposed Changes Edit
The proposed changes include an update to the web-based interface of Twitter, and functionality to allow a user to ignore ReTweets from a specific user. The interface will be modified by placing new text commands of “reply/retweet” underneath the “favourite” star button. Twitter keeps these commands hidden until the mouse is moved over them, which is why the commands aren’t visible in the tweet within the timeline above the example.