If you are using an iPhone for Twitter and your preferred app for managing your Twitter account is Tweetie2, you will notice that some tweets have a RED triangle in the top right hand corner with a RETURN ARROW clearly displayed.
If you check the Tweet - you will find that you may be following the person who is being RT'd BUT they are not following you. In most cases you do not follow them and they do not follow you, either. Neither of you are in contact. Let's call them the "Tweetee".
Usually, there is a mutual following between the person who has made the RT and yourself. (The ReTweetee) On some rare occasions, you will be following the ReTweetee who does not follow you back. They are not in contact with your Tweetstream and the only way you get their attention is to "mention" them in a public tweet. How better than with a RT of their Tweet!
So what's the point of the RED RT ALERT sign in your Tweetstream, in Tweetie2?
It lets you immediately know - in your own Tweetstream - that someone you follow, whether one of your followers or not, is ReTweeting someone you don't already know or follow. It is a quick, easy way of being alerted to someone new, with whom you already share a connection.
Next time you see a RED RT ALERT in your Tweetstream on Tweetie2, take the opportunity to introduce youself and see if you can make it a three way conversation, between yourself, someone you already follow and a friend of theirs.
There are no guarantees that they will follow you back - but it's a great way to start a conversation with a new follower - by ReTweeting them - and then suggesting you follow one another.
There is a document attached to this discussion which lists all the RTs that were included in the data base for analysis - they were received on my iPhone over a period of approximately three hours in one day.