This feature is a nice idea of Twitter Team and is very helpful to Original Twitterer's tweet. This is now going to stop the copying of tweets of original user.
Twitter itself added an option like "Retweet" on its page and users can easily anyone's tweet without copying or putting RT @.... This new implementation made the Retweeting fast.
If you are daily ReTweeter then this new option will really help you!! They even added a section called "Retweet" in their right sidebar, where you can find who is Retweeting and who retweeted your Tweets and even the retweet of yours... But you can only track those user's retweets whom you are following.
This feature helped the thousand follower holders, who are automatically getting Retweets without the help of 3rd party applications like Tweetmeme and other...