Earlier quoted context omitted.
> People have been begging for an edit button for a decade. And they haven't implemented it because it's a truly horrible idea. If you messed up your tweet delete it. If it's already got traction, then it shouldn't be changed, especially because the edit feature would mostly be used maliciously to cancel retweeters.
Retweet could show the version of the tweet as it was when it was retweeted. If you see a tweet that has a new revision ready you could see a "latest" link. If you see the latest version of a tweet with a version history you could see a "history" link which would show you a revision history.
[0] No idea how it works internally, but it would hardly surprise me if the lack of edit functionality caused early design decisions around stuff like this that would be pretty tough to unwind.